SAN DIEGO -- Investigators arrested one person and questioned at least six other people during a search of two homes as part of an investigation into a powerful pipe-bomb blast that damaged the downtown federal courts complex, it was reported Friday.

A law enforcement source who requested anonymity confirmed that Thursday's searches were part of the bomb probe and said one woman was arrested, the San Diego Union Tribune reported.

The FBI called on the San Diego Police Department shortly before 4:30 p.m. Thursday to assist in serving a search warrant at the residence at 39th and Quince streets, SDPD Detective Gary Hassen said.

Hassen said at the time he had no information on the federal case that prompted the actions, and the FBI did not immediately return telephone calls seeking comment.

Several news outlets, however, reported that the operation was believed to be related to the bombing two Sundays ago at the Edward J. Schwartz Federal Courthouse on Front Street.

Shortly after 1:30 a.m. on May 4, a homemade device made of several attached tubes packed with some type of explosive material detonated, damaging a front door and lobby area and breaking a window on a nearby building.

The non-injury bombing prompted a daylong closure of the justice hall on May 5.

Authorities said at the time that it was unclear if the incident was linked to a pipe-bombing that damaged a Federal Express building in the Webster area of San Diego in late April.