STORY: The attacker, a white man in a checked shirt, drove up to the center in a white SEAT sports utility vehicle at around 1120 GMT.
He got out and threw three petrol bombs, one of which failed to go off, the photographer said, adding that he then drove to a nearby petrol station where he killed himself.
"Officers established that two to three incendiary devices had been thrown into a Home Office immigration premises," Kent Police said in a statement.
"One minor injury has been reported. The suspect has been identified and located. Enquiries into the incident remain ongoing."
The attack comes in the midst of a highly charged political debate about immigration in Britain.