A man helps a dog suffering from heat-related injury at the Road Ranger convenience store in Lake Station on July 27.
CNN  — 

Multiple dogs being driven to a police K-9 training facility died in Indiana on Thursday after the air conditioning in the truck transporting them failed in a “freak event,” police say.

According to a Facebook post from the Lake Station Police Department, the dogs were traveling from Chicago O’Hare International Airport to Michigan City, Indiana, when the truck was caught in a two-hour traffic delay.

Along the way the air conditioner failed, causing the temperature to rise in the cargo area of the truck, according to the post. Temperatures in the Chicago area reached 92 degrees Fahrenheit on Thursday, the National Weather Service said.

“Since the cargo area was separated, the driver wasn’t aware at the time that the AC unit failed which caused some of the canines to go into heat related medical distress. The driver’s attention as to what was going on inside the cargo area was alerted to him by some of the canines barking,” police said.

The driver then stopped the vehicle at a gas station in Lake Station, Indiana – about 60 miles southeast of the airport – and saw that the dogs were in distress. He began removing the canines from their crates, which prompted 911 calls into both the Lake Station Fire Department and police department, police said.

“There was an overwhelming response from both agencies so much so that civilians and so many others stopped to help where they could,” police said.

They said the scene was chaotic and “took an emotional toll on all that were involved in trying to save as many canines as possible.”

“Any loss of life is tragic and thoughts and prayers are with all those that were affect(ed) by this ‘freak event,’” police said.

The department said it had spoken to the person involved and believes “this was not an act of animal cruelty or neglect but a mechanical failure of the AC unit that was being used in the cargo area.”

CNN’s Susannah Cullinane contributed to this report.