CNN  — 

A 22-month-old girl has died after she was found unresponsive in a minivan outside a commuter rail station in Lindenwold, New Jersey, prosecutors said.

A 911 call at about 3:38 p.m. Friday reported a child inside the van at the PATCO High Speed Line, according to a press release from the Camden County Prosecutor’s Office. Police arrived and found the girl unresponsive in her car seat and the passenger window broken, authorities said.

The toddler was pronounced dead on the scene at 3:54 p.m. Authorities did not say how long the child was inside the minivan. The investigation is ongoing and no charges have been filed at this time, the prosecutor’s office said.

Lindenwold is a suburb about 15 miles southeast of Philadelphia.

Heatstroke kills 38 children every year on average, according to the National Safety Council. These include instances in which a child has been forgotten in a vehicle, when they accidentally lock themselves in a car or trunk, and in a small number of cases, when a child has been intentionally left in a car.

The majority of heatstroke deaths occur by accident, according to NoHeatStroke.org, a data site run by San Jose University’s Department of Meteorology & Climate Science. More than half happen when parents forget about their child in the backseat. Another 26% of children die after entering a vehicle on their own, and about 19% are left there intentionally.

Last year was the deadliest year for child vehicular heatstroke in 20 years, with 52 children between 7 weeks and 5 years old dying after being left in cars, according to Amber Rollins, director of KidsandCars.org, a national nonprofit. This year, with 35 deaths so far, could surpass last year’s record, she told CNN’s Kate Bolduan Monday.

“It is a very difficult thing to understand,” said Rollins. “This is happening to wonderful parents – highly educated, responsible people.”

The fact that most people don’t believe it can happen to them is the biggest challenge in overcoming these tragedies, she added.

Common risk factors are sleep deprivation – a fact of life for most parents of young children – and a change in the normal daily routine, according to the nonprofit.

A closed car or minivan can heat up very quickly, with more than half of the total spike in temperature occurring in the first 10 minutes, Rollins explained. At the same time, a child’s body overheats 3 times faster than that of an adult.

To prevent an accidental death in an unoccupied car, always keep it locked whether you have children or not, and keep your keys in a place that children cannot reach or access, KidsAndCars.org advises. Anytime a child goes missing, any vehicles should be checked immediately – just like a swimming pool, the nonprofit suggests.

Onlookers in Lindenwold watched as police wrapped crime tape around surrounding vehicles and draped a tarp over the open sliding door of the van, CNN affiliate WPVI-TV reported.

“My heart just broke,” said Ashely Iwu, whose own car was enclosed within the police perimeter. “I can barely stand outside and so who can imagine what the temperatures are like in the car – probably in the hundreds.”

CNN’s Scottie Andrew and AJ Willingham contributed to this report.