Investigators said they are looking for the adult female victim's car, a 1989 Ford Thunderbird, as well as the vehicle's driver, The (Oklahoma City) Oklahoman reported Tuesday.

"We're looking for the vehicle as well as the person driving it," said Jessica Brown, Oklahoma State Bureau of Investigation spokeswoman. "We're hoping that person can help with a timeline" of what happened.

Jason Garas, the woman's ex-husband and the father of at least one of the children, told KOMO-TV, Oklahoma City, he believes a man was staying at the apartment, but was unaware of any problems.

Authorities found the four children and one adult Monday night, but did not detail how they died. Police said the bodies were found when an officer went to the apartment on a welfare check.

"An officer went inside the residence and found multiple dead bodies," Brown said. "He backed out and called for help."