The Los Angeles Police Department is investigating a bomb threat made to the office of Mayor Antonio Villaraigosa on Monday, just days after the nation was put on edge with a failed car-bomb attack in New York's Time Square.

The police bomb squad swept through the mayor's and other City Hall offices with bomb-sniffing dogs, and no destructive device was found, said the mayor's spokeswoman, Sarah Hamilton. The mayor was not at City Hall when his office received the threat Monday morning, and no City Hall offices were evacuated, she said.

"The LAPD was notified, and as is consistent with established protocols, all necessary measures are being taken to investigate this matter and protect employees," Hamilton said in a statement released Tuesday. "No evidence of a bomb or any sort of destructive device was located, nor has evidence been found lending credibility to this threat."

Hamilton said the investigation is ongoing.