HIALEAH, Fla. — Authorities believe that carbon monoxide from a running car killed five friends whose bodies were found in a South Florida motel room.

Hialeah Fire Department spokesman Cesar Espinosa said a maid at the Presidente Motel called 911 Monday after seeing the teenage victims unconscious through a window.

Police spokesman Carl Zogby said their deaths appear to be accidental.

A car used by the group was found running in a closed garage underneath the room. Friends said the car had needed a jump-start earlier and could have been left running to preserve the battery’s charge.

A door leading to a staircase up to the room had been left open, and high levels of carbon monoxide were found inside.

The group rented the room Sunday to celebrate one of the teens’ 19th birthday.

Officials found no alcohol, drugs or suspicious items in the room.