MOUNT PLEASANT — Police here are investigating their third grocery store robbery in a month.

Three men robbed the Piggly Wiggly at 1981 Riviera Drive at 10 p.m. Monday, according to an incident report released on Tuesday.

Witnesses told police one of the suspects had a dark revolver and another had an “auto Uzi.” The men took the money at gunpoint and ran toward the Yamato Japanese restaurant nearby.

The suspects were not found. They are described as three black males between 20 and 25 years old, ranging from 5-foot-10, to 6-foot. All were skinny. The suspects wore a red shirt, a white shirt and a black shirt. All wore bandannas over their faces and dark, baggy pants.

It was the first grocery store robbery since late June, when police responded to two in four days.

The Harris Teeter at 2195 Tea Planters Lane was robbed about 11:30 p.m. on June 26 by two black males. One of the suspects was described as 6-foot; the other as about 5-foot-6.

The Food Lion at 697 Longpoint Road was robbed about 9:15 p.m. on June 24 by several men. The suspects were all described as black males between the ages of 20 and 25. One suspect was described as being about 5-foot-8 and 165 pounds. No further descriptions were given for the other suspects.

The Charleston County Sheriff’s Office is also investigating an armed robbery at the 17 North Roadside Kitchen that happened just outside Mount Pleasant city limits about 8:30 a.m. on June 27. Both suspects are described as about 6-foot and 170 pounds. One wore a blue bandana, authorities said.