SAN FRANCISCO (KCBS/AP/BCN) — San Francisco police are on heightened alert following two deadly explosions at the finish line of the Boston Marathon on Monday, SFPD Chief Greg Suhr told KCBS. A short time after the SFPD’s announcement, Oakland police also went on heightened alert.

At least several people were killed and over 100 more injured in the blasts which Boston and federal authorities said were caused by bombs. The back-to-back blasts occurred about two hours after the marathon winners crossed the finish line.

READ MORE: Rain Helps Wash Away Fears Of Another Devastating Wildfire For Santa Rosa Couple

Deadly Boston Marathon Blasts; Top Bay Area Runner Safe
Photo Gallery: Boston Marathon Finish Line Explosions

Chief Suhr said his department had increased patrols around the city of San Francisco’s “higher-profile potential targets,” which included critical infrastructure and areas where large crowds gather. But he added that the move was a safety precaution and that the city had received no credible threats.

“We don’t really need to hear anything from anybody when something like this happens. We’ve got all the officers right now going into uniform. The uniform presence in San Francisco will be stepped up significantly especially where crowds gather,” Suhr told KCBS All News 740 Am & 106.9 FM. “There will be officers all over San Francisco and you can imagine where there will be more than less.”

The chief asked members of the public to be especially vigilant and report any suspicious activity by calling 911.

“It’s just so sad that this event has taken place. We just want to make sure we’re safe here,” Suhr explained. “Certainly if anyone sees anything whether it’s an object or person that they think is suspicious, please contact us physically or call 911 and we’ll respond.”

He added: “Err on the side of caution. Better it be nothing and we dispense with it quickly than it be something that we don’t know about and somebody gets hurt.”

The SFPD and city officials also planned to rethink security for the upcoming San Francisco Marathon in June and the Bay to Breakers foot race next month.

“We’re looking at every single event that we have scheduled,” Mayor Ed Lee said. “We have time to figure some things out.”

George Ridgley, the Bay to Breakers director of operations, said San Francisco’s annual footrace would go on despite the Boston tragedy. He said they expect about 30,000 runners and tens-of-thousands of spectators to line the route lasting from the Bay to Ocean Beach on Sunday, May 19.

Lee noted that preliminary reports indicated the Boston Marathon bombs may have been inside trashcans, and said, “we’re looking at and are sensitive to that.”

READ MORE: UPDATE: Phish Fan Injured After Being Fallen On at SF Chase Center Concert Describes Brush with Death

In Oakland, police also activated a more visible police presence in response to the Boston bombings, particularly at Monday night’s Oakland A’s baseball and Golden State Warriors basketball games. The Coliseum and adjacent Oracle Arena can hold a combined 54,000 spectators.

“Although we have no reason to believe that there is a threat in or to Oakland, we have taken a few steps to help we ensure our present level of safety is maintained,” OPD Sgt. Chris Bolton said.

In San Jose, Sgt. Jason Dwyer said the SJPD was not modifying their regular field deployment of officers or “ramping up” security at any critical infrastructure sites.

In Sacramento, emergency management officials activated a statewide threat assessment system that was first established following the Sept. 11, 2001 World Trade Center bombings.

However, acting Gov. Gavin Newsom said there was no known California connection to the explosions in Boston and no indication of any threats to California.

Meantime, there was no immediate word of heightened security at any of the Bay Area’s airports.

San Francisco International Airport spokesman Doug Yakel said SFO was waiting for direction from the Transportation Security Administration.

“The TSA typically leads the way on that, and if there’s any changes that need to be made to our security procedures, they would communicate that out,” he said.

Golden Gate Bridge spokeswoman Mary Currie said normal security procedures were in place along the iconic San Francisco span, but added that bridge district officials were “aware of the situation” and were in communication with partner agencies to ensure safety.

Bay Area Rapid Transit spokeswoman Alicia Trost said BART was on “heightened alert” and transit agency officials were closely monitoring the situation. But she noted, “We have received no information that would lead us to believe BART is a target. This was not a subway or underground bombing.”

The San Francisco Municipal Transportation Agency was working with the SFPD to increase security throughout the system and its facilities, spokesman Paul Rose said.

MORE NEWS: SF Fire Crews Battle 2-Alarm House Fire In Nob Hill

(Copyright 2013 CBS San Francisco, the Associated Press and Bay City News Service. All rights reserved.)