DALLAS (AP) — Five Dallas police officers are dead, six others injured after snipers opened fire on law enforcement in the heart of Dallas. One civilian was also hurt.

The shootings took place during a protest over fatal police shootings of black men in Louisiana and Minnesota.

Three people are in custody and a fourth suspect exchanged gunfire with authorities in a downtown parking garage.

President Barack Obama is denouncing the sniper attacks on Dallas police.

Speaking at the site of a NATO summit in Warsaw, Poland, Obama called last night's shootings a "vicious, calculated and despicable attack on law enforcement" and says "we are horrified over these events."

The president vowed that those responsible will be held "fully accountable" and that "justice will be done."