Federal officials are looking into whether a pipe bomb attack at a San Diego federal courthouse is related to a blast at a Federal Express office last month.

FBI Agent Keith Slotter said Monday that the courthouse explosion early Sunday spread nails and shrapnel as far as two blocks and someone could have been killed if they were in the area.

Evidence will be sent to an FBI laboratory in Virginia for analysis.

Slotter says a surveillance tape shows some individuals in the area shortly before the blast, but authorities have not identified suspects and no one has claimed responsibility.

Authorities say a pipe bomb shattered the door of a FedEx building early on April 25.