Nassau County police are trying to determine who stole a car — its engine running with two girls sleeping inside — in Roosevelt on Wednesday, then abandoned it Freeport.

Both girls, sisters ages 17 and 6, had minor bruises after exiting the moving car in Freeport when they realized a thief was driving, police said in a news release.

The girls’ mother, 33, pulled in front of Midway Deli at 124 Nassau Rd. in Roosevelt at about 11:10 p.m., police said.

She left the motor running and went inside, her daughters sleeping in the back seat, police said.

When the mother returned she realized her vehicle had been taken and called 911.

Meanwhile, the two girls awoke, found that their mother was not driving and “were able to exit the car at a location in Freeport when the vehicle slowed,” police said.

The girls flagged down a passing motorist who drove them home, police said.

The stolen vehicle was found abandoned on the 100 block of Merrick Road, police said, about three miles from the deli.

The sisters were taken to a hospital for treatment and evaluation; they were unable to describe the subject who was driving, police said.

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Anyone with more information can call Crime Stoppers at 800-244-8477. All information will be kept confidential.