(CNN) As the nation once again grappled with the tragedy and shock of another workplace shooting rampage, the 2020 Democratic candidates decried the failure of Congress to move gun control legislation — calling for immediate action to keep Americans safe.

Campaigning in South Carolina after a private visit Friday to the site of the 2015 mass shooting at Emanuel AME Church in Charleston, California Sen. Kamala Harris renewed her call for universal background checks and an assault weapons ban.

"We're not waiting for another tragedy to figure out that we need smart gun safety laws because we've seen every tragedy that we can imagine," Harris told a packed gymnasium of voters on Friday night in North Charleston. "We've seen assault weapons kill babies and police officers. There's no need for assault weapons in a civil society. We don't need them. Let's ban them. These are reasonable, good ideas."

Harris also called for closing the so-called "Charleston Loophole" by giving law enforcement more time to run background checks. Last week, the House Judiciary Committee advanced legislation co-sponsored by South Carolina Reps. James E. Clyburn and Joe Cunningham that would give the FBI more time to investigate the background of gun buyers to prevent those with certain mental health or criminal convictions from obtaining a gun.

Under current law, the FBI must complete background checks in three days or else the sale is cleared; the legislation would extend that period for 10 days. Advocates for the bill say it would have prevented Dylann Roof from obtaining the gun that he used to kill nine people who were worshipping at Emanuel AME in 2015.

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