Four Dallas police officers have been killed and seven wounded by sniper fire during protests against the shooting of black men by police, authorities say, the BBC reports.
Police are in a standoff with one armed man in a garage. Three other people have been detained.
Gunfire broke out at around 20:45 local time on Thursday (01:45 GMT Friday) as demonstrators marched through the city.
The protests were sparked by the deaths of Philando Castile in Minnesota and Alton Sterling in Louisiana.