A Colorado deputy was shot and killed Wednesday night after chasing the suspect of an assault call, according to the Adams County Sheriff's Office.
One man has been arrested but officials said a manhunt is underway for two other suspects.
Deputies had been chasing the man in an "assault in progress" call about 7 p.m. (local time) when they followed him behind a home in Thornton, Colorado -- a city in the Denver metropolitan area.
When deputies approached the man, he pulled out a handgun, firing at them and hitting a deputy in the chest, said Adams County Special Deputy Amanda Overton.
"It is with incredible sadness that we report that our deputy was transported and pronounced dead at the hospital," the Adams County Sheriff's Office said in a statement.
The deputy has not been identified.
"Tonight we watched as a community was on edge and a sheriff's deputy was shot while responding to a call in Adams County," Colorado Gov. John Hickenlooper tweeted. "We are deeply saddened to learn that the deputy has died from injuries sustained in the shooting Our thoughts and prayers are with the Adams County Sheriff's Office and the family and friends of the deputy killed."
Authorities said the man ran away after the shooting but has since been arrested.
Earlier this year, a deputy was shot and killed in another Denver suburb. Deputy Zackari Parrish died after a 37-year-old man barricaded himself in a bedroom and fired a rifle, striking several law enforcement officers, officials said.