Updated

Two men were arrested in Montana on suspicion of negligent homicide hours after four bodies were removed from a burned-out mobile home near Billings.

Zaccary John Kern and Robert Eric Bottenhagen, both 21 and from Billings, were arrested Thursday night without incident, said Yellowstone County Sheriff Mike Linder.

Jail records show each man faces four counts of negligent homicide and a felony arson charge.

Linder declined to comment on the relationship between the suspects and victims, whose names have not yet been released pending autopsies scheduled for Friday morning.

"We're not releasing any investigative details at this point until I get with the county attorney's office," Linder told The Associated Press Friday morning.

He added that the charges against Kern and Bottenhagen were subject to change, pending further investigation.

Firefighters were called to the mobile home in Lockwood, just northeast of Billings, shortly after 4 a.m. Thursday.

Fire crews entered the house and got the fire under control in about 10 minutes, said Lockwood Fire Chief Bill Rash.

Sheriff's deputies obtained a search warrant before removing the bodies Thursday afternoon.

Capt. Bill Michaelis said the cause of the fire and how the people were killed are still under investigation.

The Federal Bureau of Alcohol, Tobacco, Firearms and Explosives has joined the investigation.

Troy Donges, who lives across the street, told The Billings Gazette his son was listening to music when he heard a loud bang. He looked out the window, saw flames and woke up his father.

Donges said he banged on the side of the trailer to test the heat and to wake up anybody who might be inside.

"I was hitting the trailer as hard as I could with my hand," Donges said. "There was so much smoke in there, I don't know how anybody could've survived. People told me every time I hit it, it sounded like a gunshot and it woke them up."

Dale Holthues, who lives next door, said his wife called 911 while he ran to the mobile home. He tried to kick in two different doors but couldn't get them open and received no response from inside.

"We could not get any results," he said. "I don't know if they were sleeping or what."