Law enforcement sources have identified the alleged gunman who killed five police officers and wounded seven more. His name was Micah Xavier Johnson, 25, of Mesquite, Texas. Johnson apparently had no criminal record or ties to terrorism, and lived with his mother.

In a press conference Friday morning, Dallas Police Chief David Brown described the extended standoff between police and Johnson, which ended when police sent in a bomb robot that killed him. "We saw no other option but to use our bomb robot and place a device on its extension for it to detonate where the suspect was," Brown said. "Other options would have exposed our officers to grave danger. The suspect is deceased as a result of detonating the bomb."

Brown said Johnson was angry about the recent police shootings of Alton Sterling and Philando Castile, but that he was not affiliated with any larger groups, such as Black Lives Matter, which had been holding a protest nearby when Johnson began shooting. "The suspect said he was upset about Black Lives Matter," Brown said. "He said he was upset about the recent police shootings. The suspect said he was upset at white people. The suspect stated that he wanted to kill white people, especially white officers."

President Obama addressed the incident while on a trip to Poland. "There has been a vicious, calculated and despicable attack on law enforcement," he said. "Police in Dallas were on duty doing their jobs, keeping people safe, during peaceful protests.”

Initially police thought that there had been multiple snipers operating in a coordinated fashion. But now it appears that it may have been just Johnson. Three other people were arrested, but it is not clear that anyone else had actually done any shooting. Chief Brown said police would follow any lead they could find, but at the moment it is also a time for mourning.

“Our profession is hurting,” he said. “Dallas officers are hurting. We are heartbroken. There are not words to describe the atrocity that occurred to our city.”