Charles Vacca, a firearms instructor from Arizona, was shot and killed in 2014 by a 9-year-old girl who lost control of an Uzi submachine gun at a range.

His four children gathered on Capitol Hill on Tuesday with Rep. Ruben Gallego, D-Ariz., and Sen. Edward Markey, D-Mass., to demand an assault weapons ban for children.

“My siblings and I support the Second Amendment, as did our dad," said Charles Vacca’s daughter, Ashley Moser. "We believe in the rights given to us by the Constitution. We can support the Second Amendment without arming children with machine guns.”

Gallego and Markey’s bill introduced in both the House and Senate would prevent children under the age of 16 from possessing or firing machine guns or semi-automatic weapons, including at shooting ranges and gun shows.

In a similar case, an 8-year-old in Massachusetts accidentally killed himself when firing an Uzi at a gun show.

“Children should be ‘Finding Dory,’ not firing an Uzi,” Markey said. Kids are a protected category in the United States, Markey said, and are not allowed to drive cars or purchase alcohol until a certain age.

He says that standard should apply to guns as well.

Other efforts to regulate gun ownership following the deadly shooting in Orlando in June have failed to gain enough bipartisan support to pass either chamber. Gallego says this “common-sense” legislation should appeal to both parties.

After their father’s death, Vacca’s children started the online petition

encouraging youth and their parents to call on lawmakers to pass an assault weapons ban for children.

They say about 50,000 people have signed the petition since its launch a year ago.

Gun rights groups in the past have argued that there is value in teaching children how to safely and responsibly handle a firearm. The National Rifle Association declined to comment on this specific legislation.