We’re living in a brave new world with wild new technologies. Many of these—such as driver-assist software—can make life much easier. But as police in Youngstown, Ohio, discovered recently, new tech also presents new challenges.

A Youngstown Police officer reported he was responding to a call at 4:10 p.m. when he saw a car run a red light. He ran its plates and found it had been reported stolen in Austintown, Ohio. Naturally, he made a U-turn and chased the car to East Philadelphia Avenue. What happened next was completely unexpected.

The driver stopped the car on a lawn, and four people piled out. Then, the driver set the car to continue driving down the street. Without any humans aboard.

The police officer had to make a split-second decision: pursue the fleeing suspects or stop the car, which was now driving itself into traffic. He decided to chase down the unoccupied car. He thought quickly and parked his cruiser in front of it. When the car detected the cruiser, it stopped, and the officer was able to run up and shift it into park.

Ohio discovers the trouble with “self driving” cars during a police chase

Of course, a thief has always been able to put a brick on the gas pedal or find another way to keep a stolen car rolling to wreak havoc on police. But new technologies such as lane centering and adaptive cruise control mean an unoccupied car might roll a lot farther.

This car in Ohio obviously had automatic emergency braking activated if it stopped for the police cruiser. Depending on the specific model, it would have also stopped itself after several minutes because it didn’t detect anyone’s hands on the wheel. But there’s still a chance that, if it had picked up enough speed, it might not have seen pedestrians. It also could have ignored a traffic light and driven into cross-traffic. So the police officer’s decision to stop it might truly have saved lives.

While police stopped the car, the four human suspects got away—for now. They ran toward East Boston and East Florida avenues. Youngstown police are still seeking information on the suspects.