HAWAIIAN GARDENS, Calif. » Three women were found dead at a house Monday where a car was running in the garage, and three Los Angeles sheriff’s deputies had to be treated after apparently being overcome by chemical fumes.

A relative checking up on their welfare found an elderly woman dead in bedroom about 7:30 a.m., and the other two women were later found on the floor of the detached garage, where a car was running, according to the Los Angeles County Sheriff’s Department.

Deputies called to the home in the Los Angeles suburb were overcome by a strong chemical odor when they opened the garage door, investigators said. The deputies were treated at a hospital and released.

The three women were related to each other and lived at the home, sheriff’s investigators said. Their names were not immediately released.

A neighbor, Mathilda Alfaro, told KCBS-TV that the women were adult twin sisters and their mother.

Carbon monoxide was believed to be the cause of the deaths, county fire spokesman David Bantic said.

However, Los Angeles County sheriff’s officials said there were suspicious circumstances and the cause of death will be determined by the county coroner.