OAKLAND, Calif. -- Oakland police detectives released surveillance tape of the latest in a series of brazen takeover robberies by armed bandits at six restaurants in the city's upscale neighborhoods over the last two weeks and asked the public for help catching the culprits.

Police say in the latest of the robberies, four men took the cash and valuables of about a dozen customers and employees of the Milano Restaurant Sunday night.

No one was injured, but police say one of the robbers put a gun to the head of one of customers.

The incident was the second takeover robbery in Oakland during the weekend and the sixth in two weeks.

The Happy Garden Restaurant was held up by three men who robbed a dozen customers Friday night.

On March 31, a quiet night at a popular Oakland Hills pizza parlor was shattered when armed bandits brazenly walked through the door, pulled out their weapons and threatened the terrified staff and 12 patrons. The others eateries targeted since that date include Pho 84, The Rainbow Cafe and Cybelle's Pizza.

Oakland police have released surveillance tape of the incident. Investigators are asking for help in locating the four men who robbed Milano employees and restaurant patrons.

Milano's assistant manager was among the 20 people inside the restaurant when the four robbers walked in. Tuesday night is the first night she and the rest of the staff who were present during the robbery are back on the job.

Workers told us the four suspects did nothing to disguise their identities.

Oakland police edited the tape from the Milano security cameras that captured the armed robbers as they terrorized co-workers and patrons. Witnesses say two of the men were armed. One held a gun to a patron who stood up. Another robber pulled the hair of a female patron to persuade her to give up her valuables.

The assistant manager says the whole incident took only a few minutes and that police responded immediately, but the robbers got away.

Tuesday night, patrons came to offer support to the restaurant and its staff.

"It's a shame that in this day and age [people] resort to this kind of violence and you can't go out and have dinner without worrying about being robbed," said diner Dale Hooks.

Just six days earlier, Cybelle's Pizza in Oakland's Montclair neighborhood was also robbed by a man armed with a gun. Workers asked us not to reveal their identities out of fear for their safety.

"When he came in, he put the gun to my face. He pushed me to the back. We lay down on the floor," explained the still shaken worker.

Another worker said the robber ordered her to open the cash register after all three employees were told to lay down on the floor. She says she's relieved there was money in the register to hand over, because normally she transfers the cash into the safe.

"I was so scared. If there was no money in the register, what could he have done?" she asked.

We have learned that during the course of the six robberies, some witnesses were able to provide authorities with good descriptions of the suspects.

Police say it is pure luck that so far, no one's been hurt or killed during these robberies.