GRUETLI-LAAGER, TN (WRCB) - A murder investigation is underway in Grundy County. One man is dead. Another man is behind bars. It happened in Gruetli-Laager Sunday around 5:30pm Central time.

The sheriff's office says the two men were arguing outside on 60th Avenue. Friends of both the victim and the suspect say the two were close friends and were shocked to hear what happened.

"When we pulled up, we opened the door and we could hear the car start shooting and saw him going around the corner and everybody started screaming," witness Tiffney Finch said.

Investigators say the two men were arguing here near the corner of Highway 108 and 60th Avenue across from BP. Family friends say there was a cookout going on.

Investigators say Kurt Brewer left the argument, but came back-- this time with a gun and shot the other man down.

"I was just sitting by my computer and I just heard two shots and I told him I heard two shots outside," neighbor Loretta King said.

"Walked down toward the house and saw him laying there," neighbor Glenn King said.

The victim was flown to Erlanger, but died from his injuries. Kurt Brewer was arrested and faces a murder charge. The news has shocked the community, because friends and family of both say the two men were best friends-- always together.

"Always real nice guys. It's such a tragedy that, you know, things like this are happening with close friends," BP employee Beverly Layman said.

"I thought oh no, it's hard to believe, because I grew up with them," family friend Adeline Tate said.

They, along with detectives, are left trying to figure out what caused Brewer to allegedly pull the trigger on his longtime friend.

"I never thought he'd kill nobody. He always seemed pretty calm," Finch said.

It was a terrifying turn of events that neighbor and former classmate, Tiffney Finch says she can't stop replaying in her mind.

"I ain't never seen nothing like that. Pull up at a man's, wherever he's at, and just start shooting. That doesn't make a lot of sense," Finch said.

The victim's name is being withheld while the man's family is notified. We'll work to bring you the latest details as they're released.