It had been a long night for Jimmy and Hector, two K9 officers with Florida’s Hialeah Police Department. Following their overnight shift on May 27, Jimmy worked several more hours to help search for a missing senior citizen. Both dogs were probably ready for a good, long nap. But instead, they were reportedly left in the back of an SUV in their human partner’s driveway, under the broiling Florida sun. When the officer returned to his vehicle several hours later, both dogs were dead.

Dogs aren’t the only ones who have suffered agonizing deaths in vehicles recently. Last month, an 18-month-old child reportedly died after being left in a car on an 83-degree day while her mother went to work at a Panama City, Florida, elementary school. Every year, nearly 40 children in the U.S. die after being left in sweltering vehicles.

Why do these deaths keep happening? Some people still don’t realize how quickly parked cars can kill in warm weather. 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. 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.

Dogs can suffer from heatstroke in just 15 minutes, resulting in brain damage or death. It’s a horrible way to die: Many dogs bark and desperately claw at the car windows, floor and seats while their body temperature—and panic—rises. As their organs begin to shut down, many dogs lose control of their bowels, vomit, suffer heart attacks, collapse and lose consciousness.

Some drivers think it’s OK to leave their passenger in the car for “just a minute” while they go into a store or bank. But that “minute” can easily turn into a fatal 15 minutes if the errand takes longer than planned. And even if the victim survives, being trapped in a roasting-hot vehicle for any amount of time is a miserable, frightening experience.

Distraction and forgetfulness are factors in many hot-car fatalities. Parents have forgotten to drop their kids off at daycare (often after a change in routine) and realized the error only after their child was left in a sweltering vehicle all day. Making a habit of always checking the vehicle for passengers after parking can help prevent these deadly mistakes, as can placing one’s purse or briefcase on the backseat or keeping a stuffed toy in the child’s car seat and moving it to the front passenger seat as a reminder whenever the child is in the car seat.

Police officers often leave their K9 partners in a vehicle while responding to calls, and at least 20 K9 officers have baked to death in hot patrol cars in the last three years alone. PETA is urging police and K9 associations to endorse the installment of heat-alert systems in patrol cars that can sound an alarm, page an officer, attempt to start the car’s engine and automatically roll down windows when temperatures rise, potentially saving dogs’ lives.

Perhaps the most disturbing reason why hot cars claim lives every year is because, even though passersby see a dog or a child suffering, they do nothing. If you see anyone trapped in a hot car, have the driver paged in nearby stores and/or call 911 immediately. If you see signs of heatstroke (red, flushed skin with no sweating, difficulty breathing and nausea in children and restlessness, heavy panting, vomiting, lethargy and lack of coordination in dogs), get the victim out of the car and into the shade as quickly as possible, cool him or her down with water and immediately call 911 or a veterinarian.

It’s everyone’s business when a life is in danger. By watching out for hot-car victims and taking action, we can save lives this summer.