A gunman shot four staff members at a missionary training center near Denver early Sunday, killing two, after being told he couldn't spend the night. About 12 hours later and 65 miles away in Colorado Springs, a gunman fatally shot a parishioner at a megachurch and wounded four other people before a guard killed him, police said. The police chief in Arvada, a suburb about 15 miles west of Denver where the mission workers were shot, said the shootings may be related to those in Colorado Springs but declined to elaborate. No one had been captured in the Arvada shootings, authorities said. Late Sunday, Arvada police helped Colorado Springs serve a search warrant at a home in suburban Englewood, about 15 miles south of Denver, that they said could be related to the Colorado Springs shooting case. "Colorado Springs has identified its suspect, and we're there to see whether their suspect and ours are the same," said Arvada Deputy Police Chief Gary Creagor. Witness descriptions differed in each incident. A handgun was used in the shootings at the Youth With a Mission center in Arvada, while a rifle was used at the New Life Church in Colorado Springs, police said. The gunman at the New Life Church was shot and killed by a church security guard after entering the church's main foyer with high-powered rifle shortly before 1 p.m. and opening fire, Colorado Springs Police Chief Richard Myers said. Four others were wounded, Myers said. The church's 11 a.m. service had recently ended, and hundreds of people were milling about when the gunman opened fire. Nearby were parents picking up their children from the nursery. Police arrived to find that the gunman had been killed by a member of the church's armed security staff, Myers said. "There was a courageous staff member who probably saved many lives here today," Myers said. Gov. Bill Ritter ordered state authorities to help investigate. The FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were assisting. Officers found several smoke-generating devices on the church campus, Myers said. Their intended purpose wasn't clear. Three of the injured were taken to Penrose Community Hospital in Colorado Springs, said hospital spokeswoman Amy Sufak. One person was in critical condition and another in fair condition. The third was treated and released, and the fourth was treated at the scene of the shooting, Myers said. New Life was founded by the Rev. Ted Haggard, who was fired last year after a former male prostitute alleged he had a three-year cash-for-sex relationship with him. Haggard, then the president of the National Association of Evangelicals, admitted committing undisclosed "sexual immorality." The New Life church is one of Colorado's largest with about 10,000 members. The mission training program in Arvada does have a small office on the Colorado Springs church campus. About 7,000 people were on the Colorado Springs campus at the time of the shooting, Senior Pastor Brady Boyd said. Security at the church had been beefed up after the early morning shootings in Arvada, he said. That shooting happened at about 12:30 a.m. at the Youth With a Mission center in Arvada, a Denver suburb, police spokeswoman Susan Medina said. A man and a woman were killed and two men were wounded, Medina said. All four were staff members of the center, said Paul Filidis, a Colorado Springs-based spokesman with Youth With a Mission. Arvada Police Chief Don Wick, asked whether he believed there was reason to think the shootings are related, responded, "Yes, there is reason to believe that." Wick said the suspect spent several minutes speaking with people inside the dorm. Peter Warren, director of Youth With a Mission Denver, said the man asked whether he could spend the night. Several youths called on Tiffany Johnson, the center's director of hospitality. "The director of hospitality was called. That's when he opened fire," Warren said. Johnson, 26, was killed. Warren said he didn't know whether any of the students or staff knew the gunman. "We don't know why" he came to the dormitory, Warren said. Witnesses told police that the gunman was a 20-year-old white male, wearing a dark jacket and skull cap, who had a handgun and left on foot. He may have glasses or a beard. Police with dogs searched the area through the night, and residents of nearby homes were notified by reverse 911 to be on the lookout. Medina said residents were asked to look out their windows for any tracks left in the snow during the night. About 4 inches of snow had fallen in the area in the past day. In addition to Johnson, killed in Arvada was Philip Crouse, 24. Youth With a Mission said Johnson was from Minnesota and Crouse was from Alaska. The missionary center identified the wounded as Dan Griebenow, 24, of South Dakota, and Charlie Blanch, 22, whose hometown wasn't immediately known. One of the men was in critical condition, and the other was stable, police said. The missionary center is on the grounds of the Faith Bible Chapel. Cheril Morrison, wife of chapel pastor George Morrison, said Crouse had just hung up Christmas lights at her home and that Johnson was "an amazingly beautiful person." Mimi Martin, who lives near the center, said she received the warning call at about 9 a.m. warning neighbors to keep their doors and windows locked. "Why would anybody want to hurt those kids?" Martin said. Darv Smith, director of a Youth With a Mission center in Boulder, said people ranging from their late teens to their 70s undergo a 12-week course that prepares them to be missionaries. He said the center trains about 300 people a year. Filidis said staffers are usually former missionaries themselves and that the "mercy ministries" performed by trainees include orphanage work. He said he didn't know where the group being trained in Arvada was going to be sent. Youth With a Mission was started in 1960 and now has 1,100 locations with 16,000 full-time staff, Smith said. The Arvada center was founded in 1984.