In the wake of this morning's deadly bombings at an airport and Metro station in Brussels, Belgium, local officials say that security will be increased across the city, as well as at San Francisco International Airport and on BART.

The terror attacks, which at publication time had killed at least 34 people and injured hundreds more, involved "two explosions at the city’s main international airport and a third in a subway station at the heart of the city," the New York Times reports. The first two explosions were reported at 9 a.m. Brussels time at Brussels Airport. Then, at 9:11 a.m., a bomb exploded in the last car of a subway train as left Brussels' Maelbeek station.

"At least one of the two airport explosions was touched off by a suicide bomber," the Times reports. According to the Guardian, the Islamic State has claimed responsibility for the attacks.

San Francisco Mayor Ed Lee released a statement expressing sympathy for the victims, saying “On behalf of the people of San Francisco, I express our deepest sorrow for the people of Brussels after the heartless attacks carried out today. We stand with the people of Brussels and all of Belgium and stand strong against intolerance. We pray for the families of the victims of these senseless acts of violence.”

According to Lee, "San Francisco public safety agencies are closely monitoring these incidents and have reported that there is no known threat to San Francisco. However, the San Francisco Police Department is on heightened alert with extra patrols and have asked for the public’s help to report suspicious activity right away to 911."

BART spokesperson Alicia Trott echos the mayor's words, saying that though there is "no credible threat" posted for the transit system, BART police will increase their patrols.

According to KRON 4, "due to security measures BART isn’t releasing the total number of security that has been increased," but BART police "are taking all measures to ensure the safety of passengers," a duty watch commander for the transit agency says.

Down at SFO, spokesperson Doug Yakel tells CBS 5 that travelers should “expect to immediately see heightened vigilance, in the form of increased patrols” at the airport.

Yakel says that SFO is in contact with the TSA and federal law enforcement officials in an effort to determine if passenger screening procedures need to change in wake of the Brussels attacks.

In addition, San Francisco Police Department spokesperson Officer Albie Esparza says that the police will be "increasing patrols in transit areas/SFO in response to overseas attacks."

"If you see something," Trott and Esparza both said via Twitter, "say something."

Related: NYPD Intensifies Security After Brussels Terror Attacks