A pastor was killed in a string of assaults at a Forest Hill church on Monday afternoon, and the suspect was found dead after being stunned by police and arrested.

Forest Hill police said a man drove his car into the Greater Sweethome Missionary Baptist Church and then went inside to the music room, where he beat the founder and 18-year pastor Danny Kirk Sr. over the head with an electric guitar.

Police said a janitor was injured while trying to stop the assault. The janitor may have a broken jaw from the assault, police said.

The church secretary witnessed the assaults and called 911 while she barricaded herself inside an office.

The man was still attacking Kirk and the janitor when officers arrived, police said. Officers used a stun gun to restrain the man, arrested him and placed him in a police car.

According to MedStar spokesman Matt Zavadsky, the man was not breathing and had no pulse when officials later went to check on the man. He was declared dead upon arrival at John Peter Smith Hospital.

Police said only about 10 minutes had passed between the time the suspect was stunned to when he was discovered unresponsive.

Two others were transported to the hospital, including the janitor. Their conditions were not immediately known.

"My dad [is the] best guy ever," said Danny Kirk Jr., the pastor's son. "I mean, anything I needed, anything the church needed, he was going to do. [He was the] best guy ever on this side of heaven, I promise you that much."

A crowd gathered outside of the church after word of the assaults spread through the congregation and community. Two people in the crowd were given medical attention after they become overcome by grief, officials said.

"The whole church is devastated," church member Shirley Robinson said. "The whole church is destroyed. This is so senseless and so uncalled for. I don't know God's plan for this. It just doesn't make any sense to me to take pastor Kirk from us at this time."

Surveillance cameras around the buildings were operational, police said. Investigators will be reviewing the footage as they gather more information about the attacks.

Forest Hill police have requested the assistance of the Texas Rangers in the investigation.

Authorities are expected to release the name of the man accused of killing Kirk on Tuesday.

NBC 5's Frank Heinz, Lindsay Wilcox, Kevin Cokely, Greg Janda, Kevin Cokely and photojournalist Linda Angelle contributed to this report.