By Keith Coffman

DENVER (Reuters) - Owners and makers of assault-style weapons would face civil liability under a package of measures unveiled on Tuesday by top lawmakers in Colorado, a state shaken by some of the deadliest shootings in U.S. history.

The bills, introduced by Democrats who control the state legislature, could push Colorado to the forefront of a national gun control debate reignited by several mass shootings last year, including massacres of schoolchildren in Newtown, Connecticut, and moviegoers in suburban Denver.

Other states such as New York have moved to further restrict military-style assault weapons. But if the measures become law, Colorado would hold owners, manufacturers and distributors of firearms more accountable for gun violence.

Owners of semi-automatic rifles would be subject to strict liability for civil damages caused by their weapons, and state statutes that shield manufacturers, importers and dealers from such liability would be lifted.

Handguns, bolt-action rifles and shotguns would be exempt from the measure.

If passed it would put Colorado at odds with a 2005 federal law protecting gun manufacturers from being held liable for crimes committed with their products.

"Coloradans have asked us to lead on this issue, not to stand idly by while children are being gunned down in schools and movie theaters," state Senate President John Morse said at a news conference in Denver.

The Democrats, who hold a majority in both houses of the Colorado Legislature, also urged passage of bills to ban sales of high-capacity ammunition magazines and to extend background checks for gun purchases.

A previous loophole that exempted firearms sales at gun shows from background checks was closed following the 1999 Columbine High School massacre in Littleton, where two students shot a teacher and 12 students to death before committing suicide.

Columbine stood as the deadliest U.S. public school shooting on record until 20 first-graders and six adults were slain by a gunman in December at the Sandy Hook Elementary School in Newtown, Connecticut.

Sandy Hook came five months after 12 people were killed and 58 were wounded by a gunman who opened fire during the midnight screening of a Batman film in the Denver suburb of Aurora.

GOVERNOR OPEN TO DISCUSSION

Flanked by relatives of victims of the Columbine, Sandy Hook and Aurora shootings, Morse and House Speaker Mark Ferrandino also called for measures to prevent individuals under protective orders or convicted of domestic violence from possessing guns. Continued...