As emergency responders searched for one or more gunmen at a disabilities services center in Southern California, President Barack Obama was briefed on the events and politicians tweeted their outrage.
Obama was given an update from Lisa Monaco, his Homeland Security advisor, according to reporters at the White House. He asked to be kept up to date on the developing situation.
"Obviously our hearts go out to the victims," Obama told CBS News Tuesday. "And the families."
Hours before police began to pursue a dark-colored SUV in connection with the shooting, several presidential candidates and more politicians had already reached out on Twitter to say they were upset over the shooting or express support for police.
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Among the responses was former Congresswoman Gabrielle Giffords, who herself was the victim of gun violence when she was shot in the head while meeting with constituents. She called this latest shooting "Sad, awful, & frightening news" in a tweet.
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Hillary Clinton: "I refuse to accept this as normal. We must take action to stop gun violence now. -H"
Donald Trump: "California shooting looks very bad. Good luck to law enforcement and God bless. This is when our police are so appreciated!"
Jeb Bush: "Praying for the victims, their families & the San Bernardino first responders in the wake of this tragic shooting."
Martin O'Malley: "Horrifying news out of #SanBernardino. Enough is enough: it's time to stand up to the @NRA and enact meaningful gun safety laws"
Mike Huckabee: "Praying for those impacted by the shooting in California today."
Ben Carson: "My thoughts and prayers are with the shooting victims and their families in San Bernardino."
John Kasich: "My thoughts & prayers go out to those impacted by the shooting in San Bernardino, especially the first responders. -John"
George Pataki: "Praying for the victims and first responders in #SanBernardino for a quick resolution."
Bernie Sanders: "Mass shootings are becoming an almost-everyday occurrence in this country. This sickening and senseless gun violence must stop."
Chris Christie: "Praying for all those victimized by the shootings in San Bernardino, California today.
Gabrielle Giffords: "On a plane & just seeing reports of the tragedy in San Bernardino, CA. Sad, awful, & frightening news. Praying for #SanBernardino."
Sen. Dianne Feinstein: "I’m monitoring the shooting in San Bernardino closely. Absolutely heartbreaking that we’re faced with another mass shooting."
Rep. John Lewis: "How many more innocent people must be shot and killed by madmen before we do something about gun violence?
Rep. Tim Ryan: "My thoughts and prayers are with the victims and their families in #SanBernadino"
Rep. Pete Aguilar: "My deepest sympathies and prayers for the families affected by this horrific attack and for an end to this violence."
Rep. Charles Rangel: "My heart breaks yet again w/ shooting #SanBernardino. When will these stop? We can't lose another life due to #GunViolence"