The string of bank robberies began in Ventura County more than a year ago and then the crew moved on to banks in L.A. and Orange counties.
The FBI calls them the "20 Questions Bandits" because of the questions they asked during the third stickup last December at a Bank of America branch in Oxnard.
"They came in, demanded, asked where the money was, where the manager was, where the keys are, just a lot of questions more than the usual robbery," said FBI Special Agent Pat Conley.
The FBI says the robbery crew consists of at least four men believed to be African-American, and because of their agility, believed to be young. The M.O. is nearly always the same: They burst in, take over the bank and use force if employees and customers don't move fast enough. That's what happened last July at the Bank of America branch in Thousand Oaks.
"They immediately assaulted one employee and then were frustrated with a second employee because they weren't able to get into the cash area quick enough and so they got frustrated and assaulted the second employee," said Conley.
Agents say it's hard to identify the robbers from the many photos taken by bank cameras. That's because they wear masks and hooded sweatshirts, but they also wear a specific type of Easton baseball gloves, which might help police if an acquaintance knows someone who favors Easton gloves. In some robberies they display handguns but in others they simply threaten.
In almost every case the robbers hit the banks just before they close -- but not always. The Cathay Bank in Rowland Heights was robbed at 9 a.m. The FBI says it doesn't know why.
They also don't know why they're picking on Bank of America, the target of seven of their 11 heists. Most recently, last month, they hit a branch in Newport Beach.
"It appears that it could just be a matter of time before there is some type of happenstance that causes a violent encounter, and we certainly want to stop that," said FBI Special Agent in Charge Bill Lewis.
Bank of America is offering a reward of up to $100,000 for information on this robbery crew. If you know something, you can call the FBI to collect that reward through the tip line 1-888-CANT-HIDE (888-226-8443).