4-month-old baby dies after being left in hot car in Phoenix

The child appeared to have been dead for hours, authorities said.

A 4-month-old baby died Tuesday after being left inside a van in Phoenix, authorities said.

The young child appeared to have been dead for hours when firefighters arrived on scene Tuesday afternoon, as temperatures reached above 90 degrees Fahrenheit in Arizona's sun-drenched capital. The vehicle was parked outside a school district office where one of the child's parents works, according to the Phoenix Fire Department.

The Phoenix Police Department is investigating the incident.

Detectives believe the parent didn't realize the baby was in the car until leaving work for the day.

The Washington Elementary School District released a statement Tuesday evening, confirming the death of an employee's child outside its service center.

"Our hearts go out to our staff member, his family and all of his colleagues who are grieving this tragic loss," the school district said.

ABC News' Alex Stone contributed to this report.