While authorities try to piece together a motive behind Wednesday's mass shooting in California that left 14 people dead, a political battle – largely along partisan lines – played out among U.S. lawmakers.
Authorities identified Syed Farook, 28, and Tashfeen Malik, 27 – either who were a married couple or engaged – as the suspects behind the mass shooting at a center that helps developmentally disabled people in San Bernardino.
Twenty-one other people were injured in the attack.
The day after the horrific attack at the social service center, many Democrats called for action to strengthen gun laws while most Republicans focused on sending thoughts and prayers to those impacted by the attack.
The condolence messages were attacked on social media.
There has been growing frustration in the U.S. that little is being done at the legislative level in Washington regarding gun violence, despite seemingly daily frequent mass shootings.
According to the online site Mass Shooting Tracker, Wednesday's attack is the 353rd mass shooting in the U.S. so far this year. The tracker defines a mass shooting as four or more people shot in one incident.
Minority Leader Harry Reid, speaking from the Senate floor Thursday morning, called the National Rifle Association, which has contributed millions to congressional members' campaigns, a "quasi-militant wing of the Republican Party."
"Those who choose to do the NRA's bidding will be held accountable by our constituents," Reid said, calling for legislative action. "It will never be possible to prevent every shooting ... But we have a responsibility to try."
Senate Majority Leader Mitch McConnell, who followed Reid, expressed his sympathies for the shooting victims Thursday but did not mention gun legislation. On Wednesday, his office had tweeted: “The senseless loss of life in San Bernardino defies explanation.”
'Mental illness' issue
During an interview on a CBS morning news show, House Speaker Paul Ryan said mental illness is the common theme among many mass shootings in the U.S. He made a similar comment regarding last week's mass shooting that killed three people at a Planned Parenthood clinic in Colorado.
"People with mental illness are getting guns and committing these mass shootings," Ryan said. Congressional discussions regarding mental health legislation include who should and shouldn't have access to guns, he added.
House Minority Leader Nancy Pelosi, who represents California, said Thursday, “Gun violence is a crisis of epidemic proportion in our nation.
“We’ve had far too many moments of silence on the floor of the House and while it is right to respectfully acknowledge the losses, we can no longer remain silent," Pelosi added. “What gives us the right to have moments of silence when we do nothing to act upon the cause of the grief?”
She called for more gun control, legislation to expand background check requirements to include gun shows and the Internet, and for legislation to prevent individuals on the Terrorist Watchlist from obtaining guns.
Sandy Hook shooting
Senator Chris Murphy represents Connecticut, where the Sandy Hook Elementary School mass shooting killed 26 elementary students and teachers in 2012. On Wednesday, he tweeted in response to Republican lawmakers' messages of condolence, "Your 'thoughts' should be about steps to take to stop this carnage. Your 'prayers' should be for forgiveness if you do nothing – again."
On Thursday, Murphy called out his colleagues, saying in part, “Not a single senator or member of Congress can go back to their state this weekend and claim they are doing their job.”
Wednesday's shooting in San Bernardino became the deadliest mass shooting in the United States since the Sandy Hook attack.
After learning of the shootings Wednesday, President Barack Obama said, "The one thing we do know is that we have a pattern now of mass shootings in this country that has no parallel anywhere else in the world.
'Make Americans safer'
"We don’t yet know what the motives of the shooters are, but what we do know is, is that there are steps we can take to make Americans safer and that we should come together in a bipartisan basis at every level of government to make these rare as opposed to normal," Obama said while being interviewed by CBS.
Obama has recently voiced his frustration with the lack of tougher gun control laws in the country after mass shootings, such as in Oregon in October and in Colorado last week.
On Thursday, he said the motivation behind the shooting was still not yet known, but a terror attack could not yet be ruled out.
"It is possible that this was terrorist-related. But we don't know. It's also possible that this was workplace-related," Obama added.
However, Obama's statement was largely devoid of the frustration he has previously voiced.
Condolences, calls to action
Among Republican presidential candidates, most offered prayers for the victims of the shooting and their families, while some, such as Donald Trump, former Florida Governor Jeb Bush, former New York Governor George Pataki and Senator Rand Paul, also offered praise for law enforcement officials and the first responders who were involved.
Former businesswoman Carly Fiorina, who is from California, was hosting a live event on Twitter Wednesday, answering questions about her campaign while authorities sought the shooting suspects. She made no mention of the attack.
But on Thursday morning, Fiorina appeared on a cable news show "Morning Joe" and spoke to gun violence, saying authorities needed to enforce gun laws already on the books.
"We have loads of guns that are illegally owned in this country. Why don't we prosecute them?" she said.
However, the 2016 Democratic presidential candidates took to social media to call for stricter gun control laws.
Former Secretary of State Hillary Clinton tweeted on Wednesday, "I refuse to accept this as normal," and urged immediate "action to stop gun violence."
Senator Bernie Sanders also took to social media, tweeting: "Mass shootings are becoming an almost everyday occurrence in this country. This sickening and senseless gun violence must stop."
Former Maryland Governor Martin O'Malley invoked the National Rifle Association of America (NRA) on Twitter, saying the news out of San Bernardino was "horrifying" and "enough is enough." He tweeted: "It's time to stand up to the @NRA and enact meaningful gun safety laws."
The NRA made no mention of the San Bernardino shooting on its Facebook page or in its Twitter feed Wednesday or Thursday. But Colion Noir, a web series host for the NRA's media arm, responded on Twitter to criticize Clinton and O'Malley's calls for action on gun control laws.
Some material for this report came from AP and Reuters.