The gunfire ended after a parishioner subdued a man who opened fire inside an Episcopal church, the police said. Capital murder warrants were issued on Friday for the man, Robert Findlay Smith.

What started out as a relaxing potluck dinner at an Episcopal church in Alabama on Thursday evening took a sudden and deadly turn when a man pulled out a handgun and opened fire, killing three people, the authorities said.

The gunfire inside the Saint Stephen’s Episcopal Church in Vestavia Hills, Ala., ended when a fifth person subdued the gunman and held him down until the authorities arrived, Capt. Shane Ware, of the Vestavia Hills Police Department, said at a news conference on Friday.

That person, whom the authorities did not identify, “was extremely critical in saving lives,” Captain Ware said. “The person that subdued him is a hero.”