Six of them have been held up at least 14 times in the past month in Downtown and North Oakland.
A Jack In the Box on Telegraph Avenue alone has been hit five times.
Investigators say that two gunmen are responsible for some of the robberies and a lone man with a knife is responsible for the others.
So far, no one has been hurt and no customers have been robbed.
Police are offering a reward of up to $35,000 for information leading to an arrest.
