HAYWARD -- For the third time in about two months police say a masked gunman robbed a city Jack in the Box -- and this time he stuck the restaurant's employees in the fridge before making off with the loot.

The latest attack also marked the second time the same Hayward fast food franchise has been held up since May 1, police said.

Officers responded at 9:55 p.m. on Monday to the Jack in the Box at 31005 Mission Blvd. after an employee dialed 911 to report an armed robbery at the business, said Sgt. Mark Ormsby.

Witnesses told police the masked suspect entered the restaurant holding a black semi-automatic pistol and forced the employees into a refrigerator. The suspect then took $500 from the cash registers and ran out of the store.

No one was injured.

Police described the suspect as a white man, age 20-25, about 6 feet tall with a thin build. He wore a black mask covering his nose and mouth, black gloves, bluejeans and a gray hoodie.

The armed stickup marked the second time the restaurant was robbed at gunpoint in just over 60 days, police said.

During a May 1 holdup at that same store, two suspects wearing ski masks and black hooded sweatshirts entered the business about 12:01 a.m. and ordered all the employees into the kitchen.

The suspects, one armed with a small semi-automatic handgun, took cash from the registers and fled, police said.

Twenty-one days later, another Jack in the Box was hit during closing time by a masked gunman about nine miles away. During the May 22 stickup, the suspect robbed a store at 1490 West Winton Ave.

The suspect, armed with a black semi-automatic handgun, entered the business at 11:30 p.m., jumped the counter and took money from the store's cash registers, police said.

The suspect also forced the store manager to open a safe as employees laid on the ground.

He then ran out of the restaurant in an unknown direction.

Police described the suspect as a black man, age 20, 5 feet 5 inches, with a thin build. He wore a gray hoodie with the hood over his head and had his face covered with a cloth.

Police on Tuesday were investigating whether any of the robberies are related.

Anyone with information regarding the robberies is asked to call police at 510-293-7000.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.