Sen. Chris Murphy (D-Conn.) said in the wake of a mass shooting at a grocery store in Boulder, Colo., that it is time to "make our stand" on gun reform.

"This is the moment to make our stand. NOW," Murphy tweeted late Monday. "Today, our movement is stronger than the gun lobby. They are weak. We are potent. Finally, a President and a Congress that supports gun reform. No more Newtowns. No more Parklands. No more Boulders. Now — we make our stand." 

Police in Boulder say a gunman opened fire at shopping center near the University of Colorado on Monday afternoon, killing 10 people, including a police officer. 

Authorities have also not given any information regarding the type of weapon used or any background information on the alleged attacker, who is in police custody. Authorities have not given any details as to a possible motive for the shooting.

"Action is needed now to prevent this scourge from continuing to ravage our communities," Speaker Nancy Pelosi (D-Calif.) said in a statement early Tuesday. 

“While we await further information on the details of this heinous crime, we continue to stand with victims, families and young people across the country saying, ‘Enough is enough,’ " she added. "Democrats will keep fighting to end the daily tragedy of gun violence and keep our communities safe.”

A separate mass shooting at a series of massage parlors in the Atlanta area last week prompted other Democrats on Capitol Hill to speak out against gun violence. 

"We need reasonable gun reform in our country," Sen. Raphael Warnock (D-Ga.) said on Sunday. "This, this shooter was able to kill all of these folks the same day he purchased a firearm."