With shirts pulled over part of their faces, as many as three men entered Mr. T's Pizza on Sunday night just before closing time.

One pulled a handgun and they all robbed the restaurant, including the four remaining customers inside, according to Chattanooga police.

"It was pretty quick," said Tyler Grey, who was working as a manager at Mr. T's the night of the robbery. "I'm just glad nobody got hurt."

Since the robbery at the St. Elmo Mr. T's, there have been four more robberies involving what police believe are the same three to four men between the ages of 16 and 25. In two of the five cases, employees were struck on the head and, in one case, a gun was used to hit a person, said Chattanooga Police Master Patrol Officer Nathan Hartwig.

The suspects appear to be between 5 feet 7 and 6 feet tall and weigh 140 to 170 pounds, he said. Police won't release the amount of money taken from each robbery or a total amount stolen.

"We have investigators working around the clock trying to locate these guys. Patrol officers are on alert just checking our businesses," Hartwig said Tuesday during a news conference.

"We just want to make sure business owners are aware, especially at closing time. If you're a customer driving by and see something, call the police."

With the exception of Mr. T's, the assailants smashed the glass on the door and let themselves in to rob employees just after the doors were locked, Hartwig said.

Officers are encouraging anyone who encounters the group to cooperate rather than risk injury.

"I chased them out a little bit, but they had weapons," Grey said.

Police are reviewing surveillance footage from the businesses, Hartwig said.

When asked if he thinks police will catch the group, he said, "I think so."

Anyone with any information about the assailants can contact Chattanooga police at 423-698-2525.

Contact staff writer Beth Burger at bburger@times freepress.com or 423-757-6406. Follow her on Twitter at twitter.com/abburger.