Five Dallas police officers were shot dead Thursday night in Dallas, in what President Barack Obama described as a “vicious, calculated, and despicable attack.”

In addition to the five slain law enforcement officials, seven other officers and two civilians were wounded and one gunman is dead after an overnight standoff.

On Friday afternoon, thousands of people attended an interfaith service at a park in downtown Dallas to mourn the victims and condemn the violence. Across social media and in public outpourings, people from across the nation and around the world lamented the loss of life.

#Dallas Tweets

The Thursday night attack, described widely as an ambush, took place as an anti-brutality march and rally, one of many across the U.S. protesting this week’s fatal police shootings of Alton Sterling in Louisiana and Philando Castile in Minnesota, came to a close.

At a press conference Friday morning, Dallas Police Chief David Brown said the dead gunman was killed by a bomb detonated by authorities after negotiations broke down. Brown said that before he died, the suspect told police he was not affiliated with any groups and was “upset about Black Lives Matter…upset about the recent police shootings…upset at white people.”

Earlier, Brown said two shooters used sniper rifles to fire at the officers. “(They were) working together with rifles, triangulating at elevated positions in different points in the downtown area where the march ended up going,” he reportedly said.