Investigators in Broward County, Florida, are stumped by a rash of armed robberies where the suspects make their victims, including a pregnant woman, take off their clothes.

There have been five such robberies in the past two months, the last one taking place Monday night at a Subway restaurant in Margate, Florida.

Witnesses said two men wearing ski masks robbed the restaurant at about 11:15 p.m, and at least one of the men was armed.

After collecting an undisclosed amount of money, the suspects made the on-duty clerk take off her clothes. The victim was eight months pregnant, the Florida Sun-Sentinel reports.

“It seems to be that is their strategy, to take their clothes off,” Keyla Concepcion of the Broward Sheriff’s Office told NBC Miami.

In one incident that took place Oct. 31 at a Pompano Beach convenience store, the suspects shot a man in the leg because they accused him of lying about how much money he had on the premises.

All of the robberies have been caught on camera. Both suspects are believed to be between 20-25 years old, but one appears to be about 5 feet, 9 inches while the other is 5 feet, 7 inches, NBC Miami reports.

One suspect appears to have long dreads held back by a rubber band, according to a release by the Broward County Sheriff's Office.