(CNN) -- A gunman attacked worshippers at a Colorado Springs, Colorado, megachurch Sunday afternoon, killing one person and wounding four others before being killed by a security staff member, the city's police chief said.

Police would not discuss whether there was any connection between the church shootings and an attack on a missionary training center outside Denver about 12 hours earlier that left two people dead and two wounded.

The gunman in that incident was still unknown.

Chief Richard Myers called the Colorado Springs church security staffer "a courageous security staff member who probably saved many lives."

He said some of the shooting victims being treated at the hospital have life-threatening injuries.

Several "suspicious devices" were found at the church, Myers said.

SWAT teams were clearing the multiple buildings at New Life Church, along with an explosives unit, he said.

Rev. Brady Boyd, senior pastor of New Life Church, said the church had a security plan in place.

"I'm proud of the way our team responded," he said. "Many, many lives were saved because of the quick action of some committed volunteers at our church." Watch as a church member describes what he saw »

He said about 7,000 people were at the church, which had just completed a late-morning service, when the shooting took place shortly after 1 p.m.

The wounded were taken to Penrose-St. Francis Hospital, where two were in critical condition, Howard said. Another patient was in good condition and one fair, hospital spokeswoman Amy Sufak said.

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Police know neither the motive for the attack nor of any relationship between the suspect and the victims.

Police spokesman Lt. Fletcher Howard said area businesses were placed on lockdown after the shooting "to make sure there's not any other suspects at large."

As of Sunday afternoon there was no known connection between the two Colorado shootings, Howard said, but he did not rule out that possibility. Arvada, site of the missionary training center, and Colorado Springs are about 80 miles apart.

Howard said investigators are expecting detectives from Arvada to come to Colorado Springs to check for any connections between the two cases.

In Arvada, police said they were investigating whether there was any link between the two fatal shootings.

"Obviously, two shootings at two faith-based locations is very concerning to both us and Colorado Springs," said Deputy Police Chief Gary Creager.

New Life Church is on the northwestern outskirts of Colorado Springs, near the U.S. Air Force Academy. The non-denominational church claims a membership of more than 10,000.

The church was founded by the Rev. Ted Haggard, an evangelical Christian leader who was ousted in 2006 after allegations that he had been a client of a male prostitute from whom he had purchased drugs. Haggard admitted to undisclosed "sexual immorality" and called himself "a deceiver and a liar" in a letter to the congregation. E-mail to a friend

CNN's Eric Marrapodi contributed to this report.

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