Snipers operating from rooftops in Dallas killed five police officers and wounded six more in a coordinated attack during one of several protests across the country against the killing of two black men by police this week.

Dallas police shooting: US attorney general calls for "calm, peaceful and determined action"

Snipers operating from rooftops in Dallas killed five police officers and wounded six more in a coordinated attack during one of several protests across the country against the killing of two black men by police this week.