YARMOUTH, Mass. (AP) – An early morning blaze at a duplex killed a family of five who appeared to have had little or no warning that their home was on fire, fire officials said.

The two-story, wood frame duplex in the Cape Cod town of Dennis, just north of Yarmouth, was engulfed in flames when the first fire crew arrived around 1:30 a.m., officials said.

The bodies of five members of a family – a man and woman in their early 30s and two boys and one girl aged 9, 5 and 2 – were found on both floors on one side of the duplex, acting Dennis Fire Chief John Donlan said. The other side of the duplex apparently was unoccupied, and sustained less damage than the occupied section.

There were no survivors. The victims’ identities were being withheld until relatives could be notified. The Cape Cod Times reported that the victims were burned beyond recognition.

A neighbor called authorities after noticing “a huge glow” from the fire, Donlan said. Firefighters were unable to immediately enter the duplex because of the flames, and a portion of the roof collapsed.

The fire was extinguished about a half-hour after crews arrived.

The fire may have started an hour or more before firefighters arrived, Donlan said.

It appeared to have started on the first floor. There were no initial indications that the fire was suspicious, Donlan said. The cause was under investigation.

The probe could be lengthy because there were no survivors to interview and because the property damage was extensive, said Jennifer Mieth, a spokeswoman for the state Department of Fire Services.

Smoke detectors in the home apparently had not been working, Mieth said. Detectors in the unoccupied side of the duplex were found without batteries, and neighbors did not report hearing a smoke alarm from the occupied side.

“Those two things combined indicate people did not have an early warning of this fire,” Mieth said.

A middle school and elementary school that two of the fire victims had attended offered counseling for their classmates and friends.

Donlan said firefighters were shaken up by the tragedy.

“A lot of them have their own kids. I have two sons who are the same ages as the two boys who died,” he said. “It’s very difficult.”

AP-ES-10-04-04 1557EDT