Parking carelessly this summer could result in more than a ticket. It could cost a life and land you behind bars—if you leave your dog in your vehicle.

In Texas, a man allegedly left his dog to bake in a locked SUV on a 90-degree day while he cooled off at a water park. A caring passerby spotted the dog and called the police. She also posted a photo of the distressed dog on Facebook, which prompted nearly a dozen people to rush to the scene, some armed with bricks and hammers to smash a window if needed. Thankfully, a park employee was able to squeeze his hand through a tiny crack in the window to open the door. The dog survived, and the man responsible was arrested and booked on cruelty charges.

Cops are cracking down on people who leave their pups in parked cars, and they aren’t buying ignorance as an excuse. In California, a dog reportedly died after being left in a pickup truck cab in a motel parking lot for at least seven hours in high temperatures. The dog’s owner, who was sleeping inside the motel, was arrested and booked into jail on suspicion of felony cruelty to animals. And in Oregon, a woman was arrested on three counts of first-degree animal neglect after she allegedly left three dogs in a car in a restaurant parking lot for nearly four hours, killing all three of them. If convicted, she faces $18,000 in fines, jail time and/or a five-year ban on having a dog.

Leaving a dog or any living being in a parked car on a warm day isn’t much different from putting him or her in a hot oven. On a 78-degree day, the temperature inside a parked car can soar to 120 degrees in minutes, and on a 90-degree day, the interior temperature can reach 160 degrees in less than 10 minutes. People who think their dog will be fine in the car while they make a “quick stop” at the store or the bank are dead wrong. Parking in the shade, leaving the windows partially open and/or leaving water in the vehicle will not keep vehicles cool enough to be safe, either.

Trapped in a steaming car with only hot air to breathe, dogs can suffer heatstroke in just 15 minutes, resulting in brain damage or death. It’s a terrifying, painful way to die: As panic sets in, dogs frantically attempt to escape the roasting-hot vehicle by clawing at the windows or digging at the floor or seats—but this only makes them hotter. As the dogs’ organs begin to die, they lose control of their bowels, vomit, collapse and lose consciousness. Some dogs suffer heart attacks.

Dogs are especially vulnerable to heatstroke because their only means of cooling themselves is by perspiring a little bit through their footpads and by panting. That’s why it’s so important to be on the lookout for dogs who are trapped in hot cars. If you see one, have the owner paged inside the nearest store or call local animal control authorities or police immediately. Like the Good Samaritan who called the police for the dog trapped at the water park, you could save a life.

If a dog is showing signs of heatstroke—restlessness, excessive thirst, heavy panting, lethargy, dark tongue, vomiting and/or lack of coordination—get him or her into the shade immediately and call 911. Lower the animal’s body temperature gradually by providing water to drink; applying a cold towel or ice pack to the head, neck and chest; or immersing the dog in lukewarm (not ice-cold) water. Rush the animal to a veterinarian.

When temperatures warm up, no amount of time in a parked car is safe for dogs. So this summer, practice safe parking: When you’re running errands, leave your canine companion at home, with air conditioning or fans running and plenty of fresh, cool water available—and always make sure that no one is left behind in the car when you park.