America was reeling Tuesday from its second deadly mass shooting in a week, after a gunman killed 10 in a Colorado grocery store, sparking urgent new calls for political action on the fraught issue of gun control.

Tighter gun control laws are overwhelmingly popular with Americans -- and backed by incoming President Joe Biden -- but Republicans have long stood against what a minority view as any infringement on their right to bear arms.

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With a Senate Judiciary hearing on the subject already scheduled for Tuesday the familiar bipartisan divide was emerging once more, one day after a middle-aged gunman shot and killed 10 people as they bought snacks and groceries in the Colorado city of Boulder -- and just a week after a 21-year-old man shot and killed eight people at several spas in Georgia's state capital, Atlanta.

"For the second time in a week, our nation is being confronted by the epidemic of gun violence. Too many families in too many places are being forced to endure this unfathomable pain and anguish," the top Democrat in the House of Representatives, Nancy Pelosi, said in a statement.

"Action is needed now to prevent this scourge from continuing to ravage our communities," she said.

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Her call was echoed by former congresswoman Gabby Giffords, who survived a gunshot wound to the head during a 2011 assassination attempt and has advocated for arms control ever since.

"It doesn't have to be this way. It's beyond time for our leaders to take action," she tweeted.

Biden said last month he wanted Congress to pass laws that would require background checks on all gun sales and ban assault weapons and high-capacity magazines.

"This administration will not wait for the next mass shooting to heed that call," Biden said at the time.

Earlier this month the House of Representatives passed two measures aimed at enhancing background checks for gun purchases and closing a loophole related to a deadly 2015 church shooting in Charleston.

The bills address a hugely popular premise among American voters: that background checks be required for all US firearm sales, including those at gun shows.

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Tuesday's Senate Judiciary hearing will be the first of a series of hearings to examine proposals to reduce gun violence.

"It's not 'timely' that the Senate is having a hearing on gun violence prevention tomorrow," tweeted Senate Judiciary spokesman Jenna Valle-Riestra on Monday, hours after the Colorado attack.

"That's not the point. The point is that gun violence is so common in this country, we can schedule a hearing on a random date and it ends up within a week of two mass shootings," she wrote.

The city of Boulder imposed a ban on "assault-style weapons" and large-capacity gun magazines in the wake of the Parkland, Florida shooting in 2018.

But a judge last week blocked that ban, the Denver Post reported, in a decision hailed by the NRA, a powerful pro-gun advocacy group.

For its part, the NRA tweeted a copy of the Second Amendment on the right to bear arms after the Colorado shooting.

On Tuesday Biden senior adviser Cedric Richmond told MSNBC that "the regular sentiment of hearts and prayers are not enough. We need action."

"The good news is that this president has a track record of fighting against the NRA and beating them," he added.

The suspects in both the Atlanta and the Boulder shootings are in custody.

Witnesses at the King Soopers supermarket in Boulder County, 30 miles (50 kilometers) northwest of the state capital Denver, said they initially heard multiple loud bangs outside the shop.

"I just nearly got killed for getting a soda and a bag of chips," Ryan Borowski, who was in the store when he heard at least eight gunshots, told CNN.

"It doesn't feel like there's anywhere safe anymore."

Among the 10 people killed was a police officer, 51-year-old Eric Talley, who was the first on the scene.

"Didn't surprise me he was the first one there," his father, Homer Talley, told local network KUSA, saying his son "loved his family more than anything."

Colorado has previously suffered two of the most infamous mass shootings in US history -- at Columbine High School in 1999, and at a movie theater in Aurora in 2012.

Those massacres prompted nationwide soul-searching but did not result in major changes to the country's lax gun ownership laws.