Fourth Squad detectives are investigating a Valley Stream robbery in which one of the suspects used an assault rifle, Nassau County police said Wednesday.

Detectives said a man was making a delivery for a Chinese restaurant at a Marlowe Road residence at about 9:35 p.m. Tuesday.

The deliveryman stopped in the driveway when another man called out to him, police said. When the deliveryman walked toward the other man, a third man approached the victim from behind with what police said was an AK-47 rifle.

The armed man demanded money and the food from the deliveryman, made him lie on the ground and then searched his pockets, police said.

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The two suspects then ran off.

After several minutes, the victim went to his car and saw his keys were missing, as well as a cellphone and an undisclosed amount of cash.

No injuries were reported.

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