The suspect was not cooperating and told negotiators he meant to hurt more law enforcement officials, the chief said.
Brown said that before the suspect was killed, he told authorities he was targeting white police officers.
Five police officers were killed and seven others wounded after snipers targeted a crowd during a Black Lives Matter protest.
The police had been guarding a Black Lives Matter protest march; indeed some posed with marchers before the shooting expressing mutual respect and praise for the orderly demonstration.
In the aftermath of the shooting, the Dallas Police Association tweeted that the Assist the Officer Foundation has set up a donation page specifically for the Dallas officers' families. "They don't know where they're shooting, but they start shooting, and whoever was shooting started shooting back", one witness told KXAS. It appeared to be the deadliest day for US law enforcement since the 2001 terrorist attacks.
The NYPD's Counterterrorism Bureau said it was "monitoring the developing events" in Dallas, and Boston police said all its patrols would be conducted by two-officer units "in the best interests of officer safety". A woman was also taken into custody near the garage where the standoff took place.
Thursday's bloodshed, which unfolded just a few blocks from where President John F. Kennedy was slain in 1963, also evoked the trauma of the nation's tumultuous civil rights era.
"We don't feel support most days", he said. He also worked in northern Iraq and in Afghanistan, where he was a team leader and lead mentor to the southern provincial police chief.
In all, five officers were killed, including one Dallas transit cop. The mayor and police chief were seen arriving there. Krol worked in Wayne County jails in MI between 2003 and 2007 before joining the Dallas Police Department, according to WFAA. That makes Dallas police the first law enforcement agency that has ever used a robot to kill.
A vigil for Philando Castile was held in the St. Paul, Minnesota suburb where he was killed Wednesday night.