Sen. Bernie Sanders launched a vicious gun-control diatribe Thursday during the national conversation about the horrific mass shooting in San Bernardino, California.

Sanders called for a renewed assault weapons ban and universal background checks. Democrats are trying to shift the narrative toward gun control and away from the potential religious motivations that could have inspired suspect Syed Farook and his companions.

Sanders’ rival Martin O’Malley kicked off the Democrats’ gun control posturing Wednesday night, followed in short succession by Hillary Clinton, whose gun control tweet is still the top tweet on her account (though she has not added to it in 22 hours).

“We don’t know why they did it,” President Obama admitted Thursday, before calling for more gun control.