'You are your own first responder': Michigan Church security guard details confronting gunman

Jay Trombley said he had long wondered about facing an active shooter, questioning whether he would run to the confrontation or run away from it. On Sunday morning at CrossPointe Community Church in Wayne, Michigan, he got his answer.

"It was muscle memory to go take care of the threat, to protect the family," Trombley told ABC News' Detroit affiliate WXYZ.

On Sunday morning, the gunman, identified as 31-year-old Brian Browning, exited his Nissan truck wearing a tactical vest, armed with a long gun and a handgun, when he approached the church building and began firing.

Several staff members from the church approached the gunman. At least two staff members shot the gunman, causing fatal wounds, police said after the attack.

"We are grateful for the heroic actions of the church's staff members who undoubtedly saved many lives and prevented a large-scale mass shooting," Wayne Police Chief Ryan Strong said during a press conference Sunday.

Trombley, a member of the church's security team with no military or police experience, helped prevent what Wayne police Chief police Chief Ryan Strong said could have been "a large-scale mass shooting." Inside the church, worshippers first heard what sounded like a jackhammer -- what turned out to be 10 shots fired by the suspect.

"We heard that everybody kind of paused in the church for a moment," witness Dustin Fiocco told WXYZ, describing how moments of confusion quickly turned to chaos.

The incident could have been catastrophic if not for a series of events that Pastor Bobby Kelly Jr. calls "divine providence." A church member, running late to service, spotted Browning and struck him with his pickup truck, slowing the gunman's advance. That's when Trombley entered the scene and shot Browning, killing him.

"By the grace of God, he missed me," Trombley said of avoiding getting shot in the confrontation. "He hit another person in the calf. And after that, I engaged him and took care of the threat."

The other church member who was struck with a bullet underwent successful surgery and is expected to recover. Kelly revealed that Browning had a connection to the church -- his mother was baptized there, and he had attended several services over the past year.

"I don't know if it's worse if it's a stranger who has no connection to the church and just decides randomly to attack, or if it's worse when you know the person who does it," Kelly told WXYZ.

For Trombley, who considers the congregation his family, the day's events left a deep impact.

"I realize what happened yesterday, what my actions did," he said. "I will reconcile with the Lord on the time for that. I was protecting his people."

The church had recently changed plans to hold services indoors rather than outside. Kelly noted that Bible School children would have been walking through the lobby during the attack had the schedule not been altered due to vacation.

Police said Browning had no criminal history but appeared to be suffering from a mental health crisis. His exact motives remain unclear.

The Michigan State Police and a bomb squad were called to the scene, though police have not confirmed whether explosives were involved in the incident.

Trombley, who refuses to call himself a hero, emphasized a lesson from the experience: "You are your own first responder. You are the first person on scene. It doesn't matter if it's someone trying to hurt you, an injury, something -- you are your first responder."

The Wayne Police Department, assisted by local, state and federal partners, continues to investigate the incident.