Los Angeles (CNN) -- Vandals have struck President Barack Obama's campaign office in Los Angeles, police said late Thursday.
BB-gun pellets were shot and an unknown object was thrown into the office, police spokeswoman Sara Faden said.
No one was in the office at the time of the incident, she said.
The police have no one in custody and no description of the vandal or vandals.
Obama is due to hold a campaign fundraising event in Los Angeles on Monday.
An official from Obama's re-election campaign confirmed to CNN that the incident occurred but had no additional comment.
CNN's Rosaline Nieves and Kevin Bohn contributed to this report.