Sen. Joseph Lieberman (I-Conn.) on Sunday called for a restoration of a federal assault weapons ban that expired in 2004, as well the launch of a national commission aimed at preventing instances of mass violence from happening again. 

"I think we ought to restore that assault weapons ban," Lieberman said on "Fox News Sunday," during a discussion about Friday's deadly shooting at a school in his home state, in which a gunman used as semiautomatic weapon to kill 20 children and six adults. 

Lieberman also called for the launch of a commission to better understand tragedies such as the one in Newtown, Conn., and prevent them from happening again.

"I think we need a national commission on mass violence" in order to ensure that anger and heartbreak are "not lost in legislative gridlock," he said.