Two police officers have been shot dead in separate "ambush-style attacks" in Iowa, with a police sergeant warning other officers of a "clear and present danger".
Police have confirmed the officers were both ambushed in their police vehicles by "cowards" in Des Moines areas.
Scott Michael Greene, 46, was taken into custody just hours after police named him as their suspect in the ambushes.
Shooting suspect Scott Michael Greene. Source: Iowa Police
The first officer, believed to be a sergeant, was found dead about 1am local time in Urbandale, a suburb of Des Moines.
Witnesses say there are at least three bullet holes in the officer's passenger side car door at the scene.
The Iowa crime scene. Source: Twitter
The second officer was found dead about half an hour later in the city, according to local media.
"In all appearances it looks just like that, that these officers were ambushed," a clearly emotional Des Moines police sergeant Paul Parizek said.
Sergeant Paul Parizek. Source: Twitter
"It doesn't look like there was any interaction between these cowards and the officers they shot in their cars."
Sgt Parizek issued a warning to other officers as he fought back tears speaking to local media.
The second crime scene. Source: Twitter
"There's somebody out there shooting police... there is a clear and present danger to police officers right now."
At this stage, police are yet to release the names of the officers.
Greene is reportedly known to police after allegedly becoming involved in a verbal confrontation with officers just last month over his use of the Confederate flag.
At the time Greene allegedly complained his civil rights were violated by officers at Urbandale High School.
A 10-minute video posted on YouTube last month by a user calling himself Scott Greene showed an interaction with officers following an incident at a sports stadium in which he described holding up a Confederate battle flag during the playing of the US national anthem. He is heard claiming that he was assaulted.
The two officers are the first to be shot in the line of duty Des Moines since 1977, when two officers were gunned down.
The United States was on edge for weeks in July following the shootings in Dallas of five officers and a similar assault in Baton Rouge, Louisiana, where three officers were shot dead by a former military veteran.