REHOBOTH BEACH, Del. — Delaware State Police are investigating a trio of early-morning robberies in Rehoboth Beach in the last month.

Officials say the robberies occurred May 29, June 16 and June 18, and there was an attempted robbery on June 5.

The incidents have involved people being struck in the head and then robbed.

State police spokesman Cpl. Bruce Harris tells The Daily Times of Salisbury that officials are investigating whether the robberies are related.

Police say people should avoid walking by themselves early in the morning. State Police and Rehoboth Beach police are stepping up patrols in response to the robberies.