SACRAMENTO, Calif. (Reuters) - The California Assembly on Wednesday passed a package of gun control bills, including a measure to ban so-called bullet buttons which allow quick changes in the magazine of a military-style weapon.

Guns are seen inside a display case at the Cabela's store in Fort Worth, Texas, June 26, 2008. REUTERS/Jessica Rinaldi

The bills, which lawmakers are pushing the Senate to consider this month, are among several gun control measures that leaders of both houses want to pass in advance of a gun control referendum headed for the November ballot.

The measures include a ban on so-called bullet buttons which supporters say allow gun manufacturers to bypass the state’s prohibition on removable ammunition magazines. Weapons owned by the shooters in December’s San Bernardino massacre were equipped with bullet buttons.

The bill passed on the same day that the University of California, Los Angeles campus was shut down in the wake of a murder-suicide shooting.

Also passed was a bill to allow employers, co-workers, mental health workers and school employees to ask a judge to ban someone from possessing a gun for up to a year. The state already allows family members to seek such a ban, known as a gun violence restraining order, against relatives whom a judge rules are at high risk of committing violence against themselves or others with a firearm.

A spokesman for the Firearms Policy Coalition was not immediately available for comment.

Last month, the California State Senate passed its own package of bills, which would prohibit possession of large-capacity ammunition magazines, require greater scrutiny of ammunition purchasers and seek to better keep guns out of the hands of violent felons.

Led by Senate Democratic leader Kevin de Leon, California senators are rushing to pass the gun control bills in part to defuse a ballot initiative on the same subject backed by Lieutenant Governor Gavin Newsom.

Democrats in the Legislature fear that Newsom’s measure, a centerpiece of his campaign so far, along with an initiative to legalize marijuana, will draw Republicans who oppose gun control to the polls, potentially influencing other races.

De Leon, who has not endorsed Newsom or announced his own plans for 2018, has said he believes that laws passed by the Legislature are more nuanced and easily adjustable than those instead created through a referendum.

Second amendment advocates have steadfastly opposed all of the measures.