In the wake of protests against the killings of Alton Sterling and Philando Castile, 4 police officers have been shot dead by snipers.
At least eight other Dallas police officers were hit, including three that are in critical condition; three additional DART officers suffered injuries that were not life threatening in the shooting.
Police are searching for two suspects who opened fire on the officers as the rally drew to a close.
Sterling, 37, was killed in Baton Rouge, Louisiana, on Tuesday morning as two officers responded to claims of a street vendor making gun threats outside a shop.
Castile, 32, suffered deadly wounds after police pulled his car over in St Paul, Minnesota, on Wednesday night.
