A timeline of the way events unfolded during and after the attacks on the Belgian capital.
Sources say the terrorists blew up ammonium nitrate bombs.
Ibrahim El Bakraoui and younger brother Khalid were no strangers to police prior to Tuesday's suicide bombings in Brussels.
A U.K. trial revealed the travel and mission of Mohamed Abrini, the terror suspect seen in an iconic photograph from the Brussels airport attack.
Under extra security, the Brussels Airport reopened its departure hall Sunday for the first time since deadly Islamic extremist attacks in March.
The March 22 bombings of Brussels airport and subway killed more than 30 people.
The revelation came as the prosecutor formally charged Mohamed Abrini in relation to the Brussels attacks.
Mohamed Abrini, 31, was arrested and charged, along with three other men, with participating in "terrorist murders."
Another suspect was arrested over links to the Brussels bombings, Belgian authorities said Saturday as armed police swooped on a city suburb.
Several arrests were made Friday in connection with the Brussels bombings, Belgian officials said.
Belgian prosecutors previously said the suspect had fled the airport just before the two blasts hit and left behind a large bag.
Najim Laachraoui blew himself up in the Brussels airport in March.
The U.S. TSA chief witnessed firsthand the devastation of the deadly bombings at the Brussels airport and subway and is motivated to improve security.
The bodies of a American couple killed in the Brussels attacks have arrived back in Kentucky.
Brussels airport reopened to a thin stream of passengers on Sunday, 12 days after suicide bombers destroyed its departure hall and killed 16 people.
Authorities charged a third suspect Saturday in connection with a foiled French terror attack, according to the Belgian federal prosecutor.
Photographer Ketevan Kardava reunited this week with Sebastien Bellin, the victim of the Brussels terror attack she photographed that terrible day at Brussels airport.
A Texas woman married to an Air Force officer was identified Wednesday as the third American killed in last week's Brussels terrorist attacks.
The French national charged Wednesday with plotting a terrorist attack had an arsenal in his apartment.
A laptop used by one of the Brussels bombers contained "alarming" images of the Belgian prime minister's home and office, an official said Wednesday.
A Belgian newspaper released photos showing the destruction inside Zaventem Airport caused by the bomb attack on March 22.
Mason Wells, 19, and Joseph Empey, 20, were in fair condition at the University of Utah Hospital, church and hospital officials said on Tuesday.
Belgium's crisis center also said Tuesday that the number of victims is back down to 32 after it was discovered some were counted more than once.
Terrorists were apparently trying to steal radioisotopes, and some experts say detonation of a "dirty bomb" is inevitable.
The toll from the bombings also climbed to 35 early Monday.
It looks like the "man in white" is still out there.
Two more Americans were killed in last week's attacks, bringing the number to four, the State Department confirmed Sunday.
Police in Brussels surrounded a group of demonstrators about 500-strong who descended Sunday on a memorial for those killed in terror attacks earlier in the week.
Five days after 28 people were killed in the Brussels terror attacks four victims remained unidentified — an agonizing delay for families waiting on news about their loved ones.
Pope Francis urged the world in his Easter message on Sunday to use the "weapons of love" to combat the evil of "blind and brutal violence", following the attacks in Brussels.
Justin and Stephanie Shults had not been heard from since the terror attacks at an airport in Belgium.
His wife said doctors are hopeful they can start to wake him up later Saturday — just in time for Easter.
Faycal Cheffou was detained Thursday night in Brussels, but is the first to face charges in relation to the terror attacks in the Belgium capital.
Flights at Brussels Airport will not resume until at least Tuesday in the wake of this week’s deadly terror attack.
Francois Hollande said the network responsible for attacks in Brussels and Paris is in the process of being wiped out, but other groups remain.
Sascha and Alexander Pinczowski were world travelers who friends described as kind-hearted and quick to make those around them laugh.
Sascha and Alexander Pinczowski had just arrived at the Brussels Airport when two explosions went off Tuesday.
Police and troops descended Friday on a Brussels neighborhood where a suspected bomb factory was found earlier this week.
Belgian officials confirmed that one of the suicide bombers who blew themselves up at Brussels airport was a jihadi linked to the Paris attacks.
A fifth suspect in the Brussels bombings was named in media reports Friday as 28-year-old Naim al-Hamed.
Kerry also brushed off criticism that Obama should have rushed back to the U.S. from Cuba after the Brussels bombings occurred.
A glimmer of hope that an American couple was found after more than 24 hours missing in the aftermath of the Brussels attacks faded later Wednesday.
At least four Americans and two New Yorkers are still unaccounted for after the Brussels bombings, according to family members.
The family of Sascha and Alexander Pinczowski "ask for continued prayers." The siblings just arrived at the airport when the explosions occurred.
Strangers helped strangers, not because it was it was their job but because they saw fellow humans in need.
Privacy rights made Belgium a "safe haven" for ISIS, says official.
Najim left for Syria in 2013 and broke all contact with his family, his brother said Thursday.
"I am an optimist, but I actually think that it may have the reverse effect," Comey said Thursday.
Since the rise of ISIS, numerous terror plots have been thwarted in the U.K., France, Belgium and Germany.
The brothers who attacked the subway and the airport were listed in U.S. terror databases.
The brothers behind this week's Brussels bombings also spied on a top nuclear researcher in the hope of building a so-called "dirty bomb."
Officials have not said how many suspects may be involved — perhaps to avoid raising fears of terrorists in the midst.
Yassin Aanouz suffered physical injuries in the attack on Brussels Airport but is worried about another, deeper scar.
"If you have a determined terrorist who is willing to give up their life ... it's almost impossible to prevent that, an expert said.
The sources told NBC News that they are certain suspect Najim Laachraoui, 24, died at the Brussels airport Tuesday morning.
The terror attacks in Belgium shut down the Brussels airport -- stranding thousands.
Two brothers were identified as the suicide bombers behind the Brussels terror attacks on Wednesday.
Officials raised the terror threat level, shut down all public transport in the city and advised locals to stay indoors as the crisis unfolded.
European authorities are searching frantically for terrorism suspect Najim Laachraoui amid fears he has escaped authorities' clutches — again.
A confidential U.S. cable shows that Belgian officials thought they were having some success slowing the flow to Syria and tracking returned fighters.
Thousands observed a minute of silence on Wednesday, the first of three official days of mourning for the victims of the Brussels terror attacks.
The situation on the ground in Belgium continues to evolve, but here is what we know for sure.
Three Mormon missionaries based in Paris were badly hurt Tuesday by the blast at Brussels airport, the Church of Jesus Christ of Latter-day Saints confirmed.
ISIS has claimed responsibility for the bombings. The blasts at the airport and subway killed at least 31 people, and a suspect is being sought.
World monuments displayed solidarity with Belgians following the terrorist attacks in the Brussels Tuesday morning.
A massive migration wave has made it all but impossible for countries to monitor who comes and goes in many European countries.
The GOP presidential field Tuesday sparred over the proper response to the Brussels terror attacks.
Within hours of the attacks in Brussels Tuesday morning, artists posted images on social media to express solidarity with the people of Belgium.
President Obama was briefed on the Brussels terrorist attacks while on his trip in Cuba on Tuesday.
At least 31 people were killed by bombs targeting the Belgian capital's airport and subway, with three Americans among dozens of people wounded.
U.S. travel officials and law enforcement officials are on high alert after a deadly bombing at the Brussels Airport and the Belgian capital's subway.
Experts say Paris attacks' roots are much closer to home than Syria: young people turning to radical Islam because they don't feel they belong.
American Evan Lamos was reading about the explosions at Brussels airport when a blast hit the train ahead of him in the Belgian capital's subway.
Current and former European and U.S. officials say Tuesday's attacks raise questions about whether Belgium can cope with the size of its ISIS problem.
Republican presidential frontrunner said the Belgium authorities should perform "the waterboarding" to obtain more information from suspects and those questioned.
Videos and photographs belonging to the ringleader behind the Paris terror attacks offer a glimpse of his life as a "gore hero" on ISIS' front lines.
World leaders took to Twitter to condemn the attacks in Brussels while sending their condolences to the victims and solidarity with Belgium.
Multiple people are dead or wounded several explosions rocked Brussels airport and the city's subway Tuesday morning.
At least two explosions rocked Brussels Airport on Tuesday, killing and wounding "several" people. Another blast shook a metro station.