The parents of a New York teenager were charged on Tuesday with his beating death inside an upstate church, and four church members were accused of assaulting the couple's younger son, police said.

Lucas Leonard, 19, died of blunt force trauma to his body after being attacked inside the Word of Life Church in New Hartford, New York, about 50 miles (80 kms) east of Syracuse, authorities said.

A joint investigation by the New Hartford police and the New York State Police determined that a second victim, Leonard's 17-year-old brother had also been assaulted. He was in serious condition at a local hospital, a press release said.

"Several church members were interviewed throughout the day and night, and several children were secured from the church and turned over to Oneida County Child Protective Services," it said. Police have not released a motive for the attack.

A woman who lives near the church, Julie Howard, told local broadcaster WKTV "there's always been weird things going on." She said this included visits by the police and what she described as the breeding of dogs in the building.

Police did not say whether they had visited the church before.

The victims' parents, Bruce Leonard, 65, and Deborah Leonard, 59 were arraigned on Tuesday on manslaughter charges and pleaded not guilty. They were being held in lieu of $100,000 bail, each.

Four other church members were charged with assault in connection with the attack on the younger victim, police said.

It was unclear how the four church members pleaded to the assault charges or if they had obtained attorneys.