"She was definitely the rock of the church, the family, just the pillar in the community," Pastor De Lono Straham said.

His mother was fatally shot outside of his church on Parker Road and Havana Street around 2 p.m. on Sunday. She was shot after she was asked to come outside as the service ended. Aurora Police have not released the gunman's name.

"She was always ready to help, to assist. She was someone you had to stop because she did so much," Straham said. "I'm just devastated. Seeing her shot in the face, four other times in the upper torso. I don't know what to say."

Straham came outside his church to see his mother, 67-year-old Josephine Echols, on the ground after she was shot. An off-duty Denver Police officer, who is Straham's cousin, then shot the suspect. Both Echols and the gunman were killed.

Echols was loved in the community. People called her Mama Jo.

"It hurts," Straham said. "We're all devastated. This may sound crazy, but the way my mom thought, she would either want to go at the hospital or at church."

Mama Jo lived for others, Straham says. A nurse in Flint, Mich., she retired there and moved to Colorado nine years ago to continue to work. She was a dialysis nurse at a local Aurora hospital.

Aurora Police have not named the shooter and neither the police nor the church members seem to know the shooter or why he opened fire.

"Right now, as of this moment, I'm unclear what he was doing in the area, why he crashed in our parking lot, what was the reason for just coming out and shooting," Straham said.

Straham says church members heard the noise of a car crashing outside. Someone asked his mom to go and help. Straham says she did so not only because she was a nurse by trade, but because of who she was as a person.

The suspect's car had hit another car in the parking lot.

Tarell Martin, a musician with the Destiny Christian Center, was the first one out of the church. He says the suspect, a black man no one at the church recognized, started to chase after him in the parking lot while pulling the trigger.

"When I fell on the ground, I tried to get up real quick, but he was already on top of me with a gun to my head and he started shooting again but no bullets came out," Martin said.

While the suspect fiddled with the gun, Martin said he was able to get away. Then, the gun started working.

"He just started shooting at me as I was running towards the church," Martin said.

Martin escaped with a bruised arm from his encounter with the suspect. He wishes he could have done more to help Mama Jo.

"I know she's in Heaven. She left great people behind, you know," Martin said, choking up.

"[I] never really understood how she was always helping everyone else until I became an adult," Straham said. "[I] realized that's what life is about, that's what she was teaching me. That's why our whole family committed ourselves to helping people, to be there for people."

Straham says the gunman made it as far as the foyer of the church after shooting Echols. That is when the suspect was shot by the off-duty police officer.

Straham says he and his congregation are very grateful to all the people who have expressed their condolences and have prayed for the church.

Denver Police will not release the off-duty officer's name at this time. The department tells 9NEWS the officer works patrol and once he's done with his days off this week, he will be on paid administrative leave, a standard procedure when officers are involved in shootings.

Denver Police say the department does not issue officers guns - they buy their own based on provided specs. DPD will not release which district the officer works in.

9NEWS has requested to interview the officer but so far he's declined through the DPD press office.

This is a section of the Denver Police Department manual on the general duties and responsibilities of all officers:

"Officers are held to be always on duty, although periodically relieved from the routine performance of it. They are always subject to orders from a supervisory officer and to call from private persons, and the fact that they may be technically off duty shall not relieve them from the responsibility of taking proper police action in any matter coming to their attention. When there is no urgent or immediate need for police action, they may request the dispatcher to turn the matter over to officers on duty in the district, but they shall take such police action as may be required prior to the arrival of the dispatched officers."