Dive teams from the FBI and sheriff's department searched a small lake in San Bernardino, California, on Thursday as part of the investigation of last week's massacre of 14 people at a nearby county office center, a law enforcement source said.

The official declined to say what the divers were looking for in Seccombe Lake at a park a short distance north of the Inland Regional Center where the Dec. 2 shooting rampage carried out by a radicalized Islamist couple occurred.

Islamic militant groups ignored contact attempts from the wife involved in the massacre, Pakistan-born Tashfeen Malik ,in the months before she and her husband killed 14 people at a California holiday party probably, because they feared getting caught in a U.S. law enforcement sting, U.S. government sources said on Thursday.