Two police officers have been shot and killed in the Des Moines, Iowa, area in separate "ambush-style attacks".
Both officers were shot in their squad cars about 5km apart, Des Moines Chief of Police Dana Wingert told a news conference.
"There is a clear and present danger to police officers right now," he said.
"There is definitely danger out there right now."
One officer was found dead about 1am local time in Urbandale, a suburb of Des Moines. The second officer was found dead about 1.30am local time in the city, NBC News reported.
"The shootings appear to have been ambush-style attacks," a statement from the Des Moines police department said.