Authorities have not received any credible information on threats, but they have still beefed up security at local events, including the Walk Now for Autism Speaks at the Rose Bowl in Pasadena.
Extra law enforcement personnel, including undercover officers, will be stationed in areas where large crowds are expected to gather. Every bag and vehicle will be searched to ensure the safety of event attendees.
Such events include the Coachella Music and Arts Festival, the L.A. Times Festival of Books at USC, Grand Prix of Long Beach and CicLAvia.
The there-day-long Grand Prix of Long Beach draws some 170,000 spectators every year. At the sixth annual CicLAvia on Sunday, tens of thousands of people are expected to hit the pavement on their bicycles through 15 miles of streets from downtown Los Angeles to Venice Beach.
Law enforcement officials advise residents to be vigilant of their surroundings and to speak up if they see anything suspicious.
"Public safety is our profession, but it's everybody's business. Every one of you is responsible for the safety of each other, and that's my takeaway. That's how we keep this region safe. That's how we make sure that if this happens here, and it may, that we can respond to it effectively, that we can keep everybody as safe as possible," said LAPD Chief Charlie Beck.
Eyewitness News anchor Phillip Palmer is the master of ceremonies at the Walk Now for Autism Speaks event, which was scheduled to take place from 8 a.m. to 12:15 p.m.