Hearing screams for help, neighbors tried in vain to rip burglar bars off the windows of a burning house where six people were killed. The victims included three teenagers and an 11-year-old girl.

Authorities discovered the bodies of Jack and Connie Somers-Wilder, their children — Daneel, 19, Leisylle, 17, and Aimy, 11 — and friend 15-year-old Kayla Hayes, in the family's garage Sunday.

Hayes, who had spent the night at the Somers-Wilder home, lived down the street.

"I kept hollering, kept yelling because I heard them," said Gerald McKenzie, who tried to make an escape path by smashing in the window bars with a sledge hammer.

"The smoke knocked me back," he said. "Then I didn't hear them anymore. I went to the garage, then tried the back door, but I couldn't get in."

Authorities believe the victims were overcome by smoke, Oklahoma City Fire Department (search) Maj. Brian Stanaland said. The cause of death was being investigated by the state Medical Examiner's Office.

It was unclear what triggered the fire, but officials said it was reported by someone inside the house.

"We had a pretty good idea people were trapped inside, so we immediately started fighting the fire and trying to do rescue at the same time," Stanaland said.

Damage was estimated around $65,000. Officials said smoke detectors should have alerted the family to the fire.