Updated

A fast-burning fire destroyed half of a duplex home early Thursday, killing five members of a family and injuring four others, authorities said. Relatives and neighbors said the dead included several children.

Fire officials say four of the five killed were children, and that all of the victims were found on the second floor of the converted farmhouse.

The cause of the fire was not immediately known.

Neighbor Isabel Scavino said her husband woke up about 3:15 a.m. to the sound of a screaming child. She told The Associated Press they heard what sounded like either gunshots or firecrackers.

Scavino said she saw a woman running from the home with several children, and a small child in her arms.

"The fire just spread out, it was just crazy. It looked like it started on the first floor and then just spread up to the roof in about a minute," she said.

Neighbors and relatives told reporters on the scene that the victims included several children.

Fire Chief Thomas Scalera said the first floor of the destroyed portion of the home was engulfed in flames by the time firefighters arrived, making it difficult for them to quickly get access to the second story.

Middlesex County Prosecutor Bruce Kaplan said authorities were working to confirm the identities of the victims and the causes of death.

He said police and the prosecutor's office were investigating the cause of the fire.

Two volunteer firefighters received minor injuries when they were involved in a two-vehicle crash en route to the fire, Kaplan said.