Three men with handguns herded about 40 employees and customers, including children, into the storeroom of the Newark, Calif., restaurant about an hour before closing time Saturday night, the Bay Area News Group reported.
Police officers from Newark and nearby Fremont responded after receiving 911 calls at 9:58 p.m., but the suspects had fled, Newark police Sgt. Manuel Deserpa said.
The men covered up their faces so there were no suspect descriptions available, he said.
"Our detective division will be following up on this," he said. "They will be working this case."