Yellowstone County Sheriff's deputies arrested two men Thursday night in connection with four bodies found in a mobile home in Lockwood on Thursday evening, where a fire had burned early that morning.

Deputies picked up Zaccary John Kern, 21, and Robert Eric Bottenhagen, 21, both of Billings.

"They were arrested and charged with four counts of negligent homicide," said Sheriff Mike Linder. 

Kern was booked into the Yellowstone County Detention Facility, which shows an additional count of felony arson for Kern. Bottenhagen was booked in after midnight and also is listed as having a felony arson charge.  

Autopsies are planned for Friday, and the victims' names will not be released until all families are notified, said Yellowstone County Sheriff's Capt. Bill Michaelis.

A large group of family and friends stood in vigil all day at the scene of the fire.

Before the bodies were removed from the mobile home, law enforcement officials met with family members to give official word of the deaths. The bodies were taken away in vans from the Cremation and Funeral Gallery.

Deputies will continue to investigate at the home at 206 Hemlock Drive and the scene will be secured, Michaelis said.

He said officials didn’t know yet what caused the fire or how the four people died.

Lockwood Fire Chief Bill Rash said the fire was reported at 4:11 a.m. Thursday and two engines arrived seven minutes later. Smoke and flames were coming from the building's north side, which appears to be the kitchen area.

Fire crews managed to get inside the home and had the flames under control within 10 minutes, Rash said.

"They went in and were able to stage an interior offensive," he said. "The structure sustained extensive damage and there were no firefighter injuries.”

Rash said the early investigation didn't reveal anything suspicious.

By early afternoon, the Federal Bureau of Alcohol, Tobacco and Firearms had joined the investigation and the Yellowstone County Sheriff's Office had secured a search warrant for the property.

Friends and family of the victims gathered near the scene throughout the day, at times numbering two dozen. They stood outside the hazard-taped perimeter waiting for answers, many sipping from cans of Mountain Dew, smoking cigarettes and talking and laughing.

At times, the parked cars of friends and relatives stretched more 50 yards south down normally quiet tree-lined Hemlock Drive.

Shortly after 4:30 p.m., sheriff’s deputies met with a group of family and friends and confirmed the four deaths. The news spread through the group, as many cried and hugged each other.

More than 12 hours earlier, before fire crews arrived, a pair of neighbors tried to get into the burning home to see if anybody was inside.

Troy Donges lives across the street and said that a man, possibly in his early 30s, lived in the house and that he thought a woman and several children had moved out earlier in the month.

Donges' son was up listening to music when he heard a loud bang and thought an animal had hit the side of their home. He looked out the window, saw flames coming from the mobile home and woke up his dad.

"When I saw the flames, I ran outside," Donges said. "There used to be a family that lived there and that was my first thought."

He wasn't sure how hot it was inside and started banging on the side of the trailer, both 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 lives next to the mobile home that caught fire and said he was in bed when a motion light in the driveway went off, catching his and his wife's attention.

He said that once they saw the flames, he ran to the home to try to get occupants out while his wife called 911.

Holthues tried to kick in two different doors, while Donges banged on the house's sides, but couldn't get them open and received no response from inside.

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

Sheriff's deputies searched vehicles parked in front of the home. Yellow crime scene tape was placed around the driveway to the home and part of Hemlock Drive was closed to traffic.

Lockwood fire responded with 17 firefighters, two engines, a ladder truck, an ambulance and a command vehicle. NorthWestern Energy also responded.

Gazette reporter Tom Lutey contributed to this story.