Alton Sterling

The suspect in the deadly attack on Dallas police officers scrawled letters in his own blood on the walls of the parking garage where officers cornered and later killed him, the police chief said Sunday.

Police agencies across the U.S. are on edge and on guard after receiving threats and calls for violence against them on social media in the aftermath of the killings of two black men and the sniper attack that left five officers dead in Dallas. Some departments ordered officers to pair up or more generally said they were heightening security.

A prominent Black Lives Matter activist was one of several people arrested Saturday night during an often-tense protest in Louisiana that included a contingent of hundreds of people who took to the streets to call for justice and voice anger over the fatal shooting of a black man by two white police officers.

Can this really be America in 2016?