LOS ANGELES (CBS/AP) — Southland and statewide agencies remained on heightened alert Tuesday following two explosions at the Boston Marathon.

At least three people were killed, including an 8-year-old boy, and more than 170 injured when two bombs went off Monday afternoon at the marathon’s finish line on Boylston Street.

READ MORE: Captain Of San Diego Smuggling Boat Wreck Faces Federal Charges

So far, no terrorist group has claimed responsibility and no one has been arrested in connection to the incident. Authorities did serve a search warrant late Monday at an apartment in Revere, a Boston suburb, where several bags of evidence were removed, officials said.

No connection between the Boston bombing and the Southland has been established. As a precaution, however, extra security will now be added to high-profile events and locations throughout Los Angeles.

“Our vigilance has been raised,” Los Angeles County Sheriff Lee Baca said Monday in a statement. “The heightened alert…includes increased patrols to create a more visible presence where people congregate, such as government buildings, shopping centers, athletic events, and public transit. Partnering with local police and public safety agencies and other countywide efforts have been enhanced, including opening the Department Operations Center to maximize communication.”

Extra officers patrolled the Dodgers-Padres game Monday night as a precaution.

“It made me happier to find out there was security and that they were going to be taking care of it,” Dodgers fan Cathy Beas said.

“There are a lot of cops patrolling. It doesn’t bother me at all. I want to be a police officer, so I like it. It looks more professional, honestly,” fan Juan Flores said.

READ MORE: Authorities Release Video Of Dramatic Shootout In Perris That Left Suspect Dead, Deputy Injured

Similar measures will also be put in place at the STAPLES Center and at this weekend’s Long Beach Grand Prix.

Mayor Antonio Villaraigosa released a statement Monday which said, in part, “We are working closely with our law enforcement partners to monitor the situation and stand ready to aid Boston in any way possible. The LAPD and other public safety agencies will remain vigilant at all public and sporting events in Los Angeles.”

The Orange County Sheriff’s Department also has extra security in place.

“Our deputies will have an increased presence at local sporting/entertainment venues and other large gathering places,” Sheriff Sandra Hutchens said in a statement.

Deputies will maintain “high visibility” at areas such as Disneyland, Angel Stadium and the Honda Center.

Southland authorities are also counting on the public to be vigilant of suspicious activity.

MORE NEWS: LAPD Arrests And Indicts 12 Individuals In $15 Million Mortgage and Green Loan Scheme In Southern California

(TM and © Copyright 2013 CBS Local Media, a division of CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2011 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)