Nineteen people were killed when a minibus carrying civilians hit a roadside bomb in southern Afghanistan, a security official told Reuters.
Gul Mohammad, police chief of the Nahri-Seraj district, Helmand, said the device had been planted by the Taliban, NBC New reported.
The attack happened after at least 19 people were killed and 35 civilians were wounded by suicide attackers in Tirin Kot, Uruzgan province, Thursday, according to provincial officials.
Twelve of the dead were children, aged between 5 and 13.
The attack began with two remote-controlled car bombs, one in front of the provincial governor's compound and the other near the offices for regional state television channel, Uruzgan TV, said the governor's spokesman, Ahmad Milad Modaser.
Up to six suicide bombers then stormed the governor's compound and the police chief's compound, said Interior Ministry spokesman Sediq Sediqqi.
Three bombers detonated their explosives shortly after the attacks began while the remaining attackers were locked in a hours-long gunfight with police inside the compounds, he added.
Modaser said two women were killed along with three adult male civilians and two police officers.
Taliban claim responsibility
The high toll of young children may have been from families trying to get national identity numbers for their children, which are required to enroll in government schools and only available at the provincial governor's office.
The Taliban claimed responsibility for the attack and spokesman Qari Yousuf Ahmadi said six militants were involved.
On Wednesday, the mayor of Kandahar was killing by a suicide attacker who officials said appeared to have hidden the bomb in his turban.
Afghan president Hamid Karzai condemned the assault, but blamed it on outside interference.
"Enemies of Afghanistan who can do nothing but harm the innocent people of Afghanistan want to do these activities for their foreign masters," he said in a statement.
It was the deadliest attack in southern Afghanistan, the Taliban's heartland, since a February assault on the provincial police headquarters in the city of Kandahar, that also killed 19.
The region has been the focus of intense NATO fighting in recent months, which has squeezed insurgents in their rural heartlands and brought some improvements in security.
Fears of instability
But the more recent high-profile killings have had an equally chilling effect on both ordinary and elite Afghans as the larger-scale attacks, kindling fears of increased instability across an already volatile region.
On July 17, gunmen killed a former governor of Uruzgan and close adviser of Karzai in his home in the Afghan capital, Kabul. A lawmaker from the same province who was visiting Jan Mohammad Khan, was also killed in the attack.
That attack came only days after the killing of Ahmad Wali Karzai, a half-brother of the president and one of the most powerful and controversial men in southern Afghanistan.
Insurgents have stepped up an effective assassination campaign targeting Afghan government officials. More than half of all targeted killings in Afghanistan between April and June were also carried out in Kandahar, according to a U.N. report.
The assassinations have left a power vacuum in the south of the country that could weaken the president's hold on a critical area that has long been a Taliban stronghold.
Violence in Afghanistan is at its worst since U.S.-backed Afghan forces toppled the Taliban government in late 2001, with high foreign troop deaths and record civilian casualties.