WASHINGTON -- A shooting at a suburban Washington state high school on Friday is likely to intensify an already heated debate over two competing state ballot measures related to gun background checks, both of which will go before voters on Nov. 4.

Information on the shooting was still emerging Friday afternoon, but multiple reports describe a lone gunman opening fire on the school cafeteria at Marysville Pilchuck High School, in Marysville, Washington. At least four students were injured and one was killed, not including the shooter. Several media outlets have reported that the gunman, who has not yet been publicly identified by authorities, was dead of a self-inflicted gunshot wound at the scene. It is unclear how he acquired the weapon.

The two ballot measures relate to gun background checks: One expands background checks for gun sales, and the other limits them. Initiative 594 would require background checks for all gun sales, including those at gun shows and online. Federal law currently exempts certain types of private gun sales from background check requirements, a feature of the law frequently referred to as the "gun show loophole." The other ballot measure, Initiative 591, would prohibit gun sellers from performing background checks on buyers unless federal law explicitly requires them to do so.

According to a poll released Oct. 13 by Elway Poll, 60 percent of Washington voters supported Initiative 594, requiring the universal background checks. By contrast Initiative 591, had just 39 percent support, suggesting it is unlikely to pass.

The dueling ballot measures are the only two gun background check initiatives in the nation that will go before voters this November. As a result, Washington state has become a hotbed of political spending by gun rights groups like the National Rifle Association, as well as by gun safety groups.

Earlier this month, the NRA released an online ad attacking Initiative 594, claiming it would waste "scarce law enforcement resources on something that will not make Washington safer."

Former New York City mayor Michael Bloomberg, meanwhile, pledged to spend up to $50 million this year to prevent gun violence. Part of that money will be spent through his gun safety group, Everytown For Gun Safety, which has spent $2 million in support of Initiative 594.