A thief swiped a car with a baby on board in Queens on Thursday morning — after a babysitter left the vehicle running, cops said.

The idling car was parked near Hollis Avenue and 190th Street with the 4-month-old in the back when it was stolen around 8:45 a.m., according to police.

The kid and car were located about four blocks away at 195th Street and 99th Avenue “a short time later,” a police spokeswoman said. The child was unharmed.

There were no arrests.