MINEOLA - Nassau County is cracking down on limousine companies that provide cars for proms and graduations that haven't been registered to operate in the county.

The Office of Consumer Affairs says since it has started the crackdown on prom limos, it has found alcohol in the cars, in addition to many improperly registered vehicles and drivers.

The county licenses limos to insure drivers have criminal background checks and that the vehicles are safe. Officials say parents should look for Nassau TLC plates and a diamond-shaped sticker on the windshield.

Kenneth Heino, of Nassau Consumer Affairs, says one way to determine if the car is registered in the county is by looking at the license plate number: It is supposed to start with an N and end with a C.

Officials say parents shouldn't hesitate to ask the limo operators to see their personal driver's license and their limo hack license before letting their children in.

Nassau County Consumer Affairs says it has issued more than 150 summonses and impounded 10 limos this prom season alone. Operating a limo without proper registration can come with a fine of more than $1,000.