The suspect in a Georgia elementary school shooting who fired six rounds in a front office before surrendering to police had nearly 500 rounds of ammunition with him, authorities said Wednesday.
Michael Brandon Hill, 20, walked into Ronald E. McNair Discovery Learning Academy in Decatur, Ga., outside Atlanta with an AK-47 type assault rifle, along with bags containing hundreds of rounds of ammunition and a couple of magazines on Tuesday, DeKalb County officials announced at a press conference on Wednesday.
On Wednesday, DeKalb County lead investigator Ray Davis and police chief Cedric Alexander outlined what could have been a massacre for the school, but ended with nobody hurt. The suspect surrendered peacefully to police after exchanging gunfire with them.
"He walked in with 498 rounds of ammunition. Fortunately this came to an end quietly, without incident," Alexander said. "I think we can all make a reasonable assumption he came here to do some harm."
Hill "did not have anything else in the bag that would harm people," Davis told reporters. Only one weapon was recovered, authorities said Wednesday, contradicting earlier reports that he had multiple firearms.
As part of their investigation, authorities are looking to locate the owner of the AK-47, who they believe is an acquaintance of Hill's. Davis said officials believe Hill got the weapon from an acquaintance's house, although he wouldn't say whether the weapon was stolen or not.
A photo of Hill holding a rifle, believed to be the same one used in Tuesday's shooting, was found on Hill's cellphone, Davis said.
The rifle was a .762-caliber AK-47-style weapon, manufactured by Romarm/Cugar. Authorities don't believe Hill owned the gun, but rather obtained it from someone else who had purchased it legally from a licensed dealer. They were working to find the gun's owner, but wouldn't say if it was stolen or not.
Also Wednesday, the brother of Michael Brandon Hill, said Hill previously threatened to shoot him and that he suffers from mental disorders.
Timothy Hill told NBC News his brother "was bipolar and suffered from ADD," and that the two have not spoken recently.
Davis said Hill told investigators he was on medication.
"He indicated that he was on medication and had stopped taking it," Davis said.
NBC has not been able to independently confirm the diagnoses of Hill.
Hill waived his first appearance in DeKalb Magistrate Court Wednesday afternoon.
Hill is charged with aggravated assault on a police officer, making terroristic threats and possession of a firearm by a convicted felon. He was questioned for hours by police, but police have no clear idea of what may be a motive or whether Hill has ties to the school.
Police chief Alexander said Hill "may have had prior contact" with someone at the school, but the investigation was still pending.
No other individuals are expected to be charged.
A sheriff's official in Henry County, Ga., south of Atlanta, said Hill was also charged there in March with making terroristic threats — a felony in Georgia. The indictment is for an incident between Dec. 30 and 31 of 2012 to "unlawfully threaten to commit the crime of murder, a crime of violence, for the purpose of terrorizing another."
Timothy Hill told NBC News the charge stemmed from Hill threatening to shoot him. Michael Hill was issued a no-contact order afterwards, Timothy Hill said.
Court records show that Hill pleaded guilty and was sentenced to three years' probation and anger counseling.
Buses transported elementary school students from their school to nearby McNair High School on Wednesday to resume classes, The Atlanta Journal-Constitution reported, a day after a potential massacre was averted.
Students were greeted by counselors and a sign that read, "Welcome McNair Elementary School. Our prayers are with you," WSB in Atlanta reported.
Officials believe the gunman walked into the front office of the school Tuesday afternoon at about 1 p.m. ET with an AK-47, despite the school security system that requires visitors to be buzzed in. He may have followed behind someone who was authorized to be in the building, but never got past the front office.
Once he was inside, the gunman told a clerk to call Atlanta TV station WSB. The clerk told a WSB assignment editor, Lacey LeCroy, that the gunman wanted the station to "start filming as police die."
"All the time of doing this, I never experienced anything like this," LeCroy said. "It didn't take long to know that this was serious."
Inside the front office, he held one or two employees captive for a period of time. School bookkeeper Antoinette Tuff said she was one of the hostages.
In an interview with ABC News, Tuff said she tried to convince the gunman to put down his guns. She said the gunman told her he had no reason to live because nobody loved him.
"And I just explained to him that I loved him," Tuff told ABC News. "I didn't know much about him. I didn't know his name but I did love him and it was scary because I knew at that moment he was ready to take my life along with his, and if I didn't say the right thing, then we all would be dead."
Tuff also said the suspect told her he hadn't taken his medication.
In an effort to calm him down, she told him about her own troubles: how her marriage fell apart and about her struggles with opening her own business.
"I told him, 'OK, we all have situations in our lives," she said. "It was going to be OK. If I could recover, he could, too."
During the standoff, Tuff told ABC News the gunman "went outside several times and shot at police officers." He had a bag "full of ammunitions," she said, but after they had talked, she asked him to put his guns down and empty his backpack.
Police chief Alexander said the suspect fired about six rounds while officers from at least a half-dozen law enforcement agencies that raced from the school returned fire.
Ultimately, Hill surrendered without incident.
Tuff, who said prayer helped her get through the ordeal, is expected to be at work on Wednesday.
"Yes, I will be back," she told ABC News," sitting in that same seat, blessing that next person."
On Wednesday, Alexander sung Tuff's praises.
"She was in there, she was able to talk him down," he said. "She's a real hero in all this."
NBC's Tom Winter and Alex Johnson contributed to this report. The Associated Press also contributed.