ELIZABETH — Maria Fernandes worked four jobs, including shifts at two different Dunkin Donuts.

Often she drove from job to job, stopping along the road to catch a couple hours sleep, police said. She kept a container of gasoline in her 2001 Kia Sportage because occasionally she ran out of gas, authorities said.

Early Monday, the 32-year-old Newark woman pulled into a lot off Route 1 & 9 in Elizabeth for a nap. She apparently left the car running and was overcome by carbon monoxide mixed with fumes from the gas can that had overturned, police said. Fernandes was found dead in the car about eight hours later.

"This sounds like someone who tried desperately to work and make ends meet, and met with a tragic accident," Elizabeth police Lt. Daniel Saulnier said.

An autopsy today failed to determine the cause of death, and police are awaiting results of toxicology tests, Saulnier said. He said no foul play is suspected.

At 3:51 p.m., city EMTs responded a 911 call of a woman found in a vehicle in a corner of the WAWA convenience store on the northbound side of Routes 1 & 9. Emergency workers found all the windows and doors on the vehicle closed and when they got inside, they were hit with a chemical odor, authorities said.

After determining the woman in the vehicle, later identified as Fernandes, was dead, the emergency responders called in Union County's Hazmat workers.

City police and firefighters, and staff from the county medical examiner's office, waited four hours while Hazmat members monitored the levels of the odors until they determined it was safe for others to enter the Kia, authorities said.

New Jersey has tens of thousands of people working multiple jobs, said Carl Van Horn, director of the John J. Heldrich Center for Workforce Development at Rutgers University in New Brunswick.

"These are are folks who would like to work full-time but they can't find the jobs," Van Horn said. "They wind up in these circumstances in which they are exhausted. More commonly it creates just an enormous amount of stress," he said.

Many people have been forced to work two or three part time jobs after losing a full-time position in the recession of 2008.

The federal Bureau of Labor Statistics estimates that 7.5 million people nationwide are working more than one job, Van Horn said, and those jobs still leave people with less income than their full-time work.

"The average person who lost their job took a 10 percent pay cut (after returning to the workforce)," Van Horn said.

Elizabeth police reached Fernandes's sister in Portugal this afternoon, Saulnier. They were still seeking a brother, who is an over-the-road trucker and out-of-state, the lieutenant said.

Tom Haydon may be reached at thaydon@starledger.com. Follow him on Twitter NJ.com on Facebook. Stay up-to-the-minute with the latest Union County news by bookmarking nj.com/union.