A gunman shot four staff members at a missionary training centre near Denver early Sunday, killing two, after being told he couldn't spend the night.

A police officer directs worshippers from a parking lot near a youth ministry dormitory on the Faith Bible Church campus in Arvada, Colo.
(David Zalubowski/Associated Press)

In another incident 12 hours later, a gunman fatally shot a parishioner at a megachurch in Colorado Springs, about 105 kilometres away, and wounded four other people before a guard killed him, police said.

The police chief in Arvada, a suburb 25 kilometres west of Denver where the mission workers were shot, said the shootings may be related to those at the Colorado Springs church but declined to elaborate. Arvada authorities said no one had been captured in the shootings there.

Colorado Governor Bill Ritter has ordered state authorities to assist in the investigation.

Police have identified the dead in the Arvada shooting as 26-year-old Tiffany Johnson of Minnesota and 23-year-old Philip Crouse of Alaska.

New Life Church was founded by the Reverend Ted Haggard, who was fired last year after a former male prostitute alleged he had a three-year, cash-for-sex relationship with him.

The church is one of Colorado's largest with about 10,000 members.