Downtown Dallas was in lockdown early Friday after what appeared to be one attacker shot 12 officers, five fatally, during a protest over deadly police shootings of black men elsewhere.
The suspected shooter was identified as Micah Xavier Johnson, age 25, a senior law enforcement official told NBC News. Johnson is from the Dallas area and had served in the Army Reserves for six years with a tour of duty in Afghanistan, NBC news reported.
The suspect exchanged gunfire with authorities in a parking garage at El Centro College into the morning, Dallas Police Chief David Brown said. He was killed by a detonation device in the standoff with police, Brown said. Three other people had been detained in connection with the shootings, but officials didn't name them or say why they were being held, the New York Times reported.
The Dallas police chief said his department would not reveal names, or how many suspects there are in the ongoing investigation.
Earlier, officials said 11 officers were shot, and updated the total later in the morning.
The "ambush-style" attack began around 9 p.m. local time, when the sniper fired at police officers from an elevated position, the Dallas Police Department said. It appeared to be the deadliest attack on law enforcement in the U.S. since the 9/11 attacks.
The White House said investigators in Dallas have ruled out any connection to terrorist investigations, according to Reuters.
Dallas Police Chief Brown shared comments from the suspect during a press conference Friday morning. Police negotiated with the suspect for hours before sending in a robot equipped with a bomb, which eventually killed the shooter, Brown said.
Police said that portions of the crime scene locations in downtown Dallas will remain closed to the public until Wednesday.
Detectives found bomb making materials, ballistic vests, rifles, ammunition and a personal journal of combat tactics while searching the suspect's home. The police said that detectives are in the process of analyzing the information in the journal.