Motorists who start their cars to warm them up and defrost the windshields and then run back inside the house are on the wrong side of the law in Lancaster city.

Same goes for motorists who leave the car running when they pull up at a convenience store to buy a gallon of milk.

City police warn that either of those moves can end with a stolen car or a $300 fine.

City police will conduct special details in the weeks ahead to find violators of a city ordinance that prohibits motorists from from leaving unattended cars running, according to Lt. Todd Umstead.

"The auto-theft unit will be especially looking for unattended vehicles with keys in the ignition and the engine running," he said. "The details are usually decided last minute, when a cold snap hits."

Police are not trying to ruin motorists' days, Umstead said. He said they're protecting residents from car thefts.

A car thief could lead police on a high-speed chase that could injure residents and officers, he said.

"If keys are left in the ignition, it is an easy opportunity, basically an invitation, for somebody to steal the car," Umstead said.

If the officer can find the owner of the car left running, the owner could be cited and given his keys, Umstead said. Officers also have the authority to seize the keys, requiring them to be picked up at police headquarters, the officer said.

Umstead said remote starter devices that disable a vehicle if someone tries to move it without the key in the ignition are allowed.

The city is not alone in prohibiting motorists from leaving unattended cars left running, he said. Umstead said the Pennsylvania vehicle code also does not allow motorists to leave unattended cars running.

The number of thefts of unattended cars left running have dropped in the city, Umstead said.

rrobinson@lnpnews.com