The pastor killed 21-year-old Jordan Caldwell after intervening in a violent confrontation between the son and a woman at around 2 p.m. at their home in suburban Philadelphia, Darby Borough police said Friday.
Kirk Caldwell fired a single shot, striking his son in the chest, police Chief Robert Smythe said. Jordan Caldwell died at a hospital shortly afterward, police said.
Smythe, who noted he had met Caldwell a couple of times, called the pastor a "very good man" and said he was "quite surprised."
"I find this is not something I would expect this guy to do," Smythe said.
As a pastor at End Times Harvest Mission for Christ in Philadelphia, Kirk Caldwell had spoken against violence at a vigil for a slain teen in Darby last summer.
"Retaliation is never the answer. Retaliation is only going to make it worse," Caldwell said, according to the Daily Times of Delaware County.
Donald Mosby, 81, who has lived next door to Caldwell for a couple of years, said the pastor also worked as a plumber and seemed "like a moderate man."
He said Caldwell used to shuttle parishioners to and from church in his vans.
The 44-year-old Caldwell had not been charged as of Friday evening. The gun was legally registered to him, Smythe said.