WILLIAMSPORT, Pa. -- Authorities say the death of a 4-year-old Pennsylvania girl who was left in a car for hours on a hot day apparently was an accident, although negligence may have been involved.

Lycoming County coroner Charles Kiessling Jr. said an autopsy didn't provide a definitive cause for Samaria Motyka's death Friday. Williamsport police expect toxicology tests to take several weeks.

A woman who was supposed to take the child to a day care center instead drove to downtown Williamsport then went to work, leaving the girl unattended in the vehicle for several hours, police agent Raymond Kontz III said. Temperatures would have been in the high 90s at the time, according to the National Weather Service.

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"We don't know how the woman could have left the girl in the back of the car," Koontz said. "That is still under investigation."

Assistant Chief Timothy Miller said that while negligence may have been involved, it appears the death was a tragic accident. He said the woman was in a relationship with the girl's father and regularly cared for her.

She is remorseful and cooperating with investigators, including taking a blood test for drug or alcohol consumption, Miller said.

In Alabama last week, police said a toddler was fighting for her life after being found unconscious in a hot car in Birmingham.

Birmingham police Lt. Sean Edwards tells CBS affiliate WIAT-TV the 1-year-old girl was found Thursday afternoon after being left in the car in downtown Birmingham.

"The reality is that there shouldn't be that much in your life that will have you so occupied that you will leave your 1-year-old child in a car, extremely hot, like a hot day, like a summer day, today," Edwards told WIAT-TV. "It's just mind-blowing to a lot of us staff. You can tell that the officers are still kinda in shock. A lot of us are at the hospital, just kind of waiting around. We're very hopeful. We believe in miracles, plus the little kid is fighting."