What was supposed to be a protest for peace in Dallas Thursday night took a deadly turn when snipers began firing at police officers. About 1,000 people had gathered in the Texas city to speak out and march after videos emerged this week of two officer-involved shootings that led to the deaths of Alton Sterling, 37, in Baton Rouge, La., and Philando Castile, 32, in Falcon Heights, Minn. The protest began at 7 p.m. at the Belo Garden Park off Main Street in downtown Dallas. Before the shooting began, the tone was generally cordial, and many officers posed for selfies with protesters. Here is USA Today’s timeline of the events that followed.