Police are investigating whether three robberies that occurred Friday night in Rockville Centre and South Hempstead are related.

Police say the three crimes happened less than two hours apart in a three-mile radius. In two of the cases, victims reported being robbed by a group of four men. The third was attacked from behind and did not get a look at his attackers.

The first incident happened on South Forrest Avenue in Rockville Centre, in which two men reported being jumped by a group of four black men. The second occurred about a half hour later at the corner of Long Beach Road and Olive Boulevard in South Hempstead. In that case, police say a man was beaten and robbed of cash and a cell phone. The third happened on the corner of Lee and Cedar avenues in Rockville Centre. The victim says four men in a car approached and threatened him with a gun.