LOS ANGELES, Dec. 23 (Xinhua) -- Los Angeles law enforcement Friday asked residents to be vigilant and engaged during the holiday week, even though there were no special threats in southern California so far.

At a joint press conference held by Los Angeles Police Department (LAPD), Los Angeles County Sheriff's Department and the FBI, representatives said they are working together to beef up security to prevent any incidents while calling on help from the public.

Officials said in a video clips posted online it most likely won't be a member of the law enforcement community that uncovers a terrorist plot.

"It's probably going to be someone in a regular residential community who's going to notice something suspicious," said Horace Frank, deputy chief of the LAPD Counter Terrorism Unit. "They're the ones that are living in the communities, they know their communities best. They know what is out of the ordinary."

To celebrate Christmas and New Year, there are many events in Los Angeles, including a countdown party in front of City Hall and the annual Rose Parade and Rose Bowl football match in the eastern historic city of Pasadena, which attract hundreds of thousands people every year.

Thursday's car attack injured 16 people in downtown Melbourne, Australia is the latest example of terror focused on large crowds, the police warned.