Gun shows in a state with weak gun restrictions increase the short-term risk for firearm-related injuries, a new analysis has found.

Researchers studied deaths, emergency department visits and hospitalizations related to firearms before and after 915 gun shows in California and Nevada from 2005 to 2013. California has laws requiring background checks, waiting periods, documentation and Department of Justice surveillance at gun shows. Nevada has no regulations pertaining explicitly to gun shows.

When gun shows were held in California, there was no difference between rates of firearm incidents in the two weeks before and the two weeks after the shows. But after Nevada shows, incident rates rose 69 percent in regions of California within two hours’ driving distance. The study is in the Annals of Internal Medicine.

“We’re seeing a pattern that suggests that California’s strict gun regulations may be effective in preventing short-term increases in firearm injuries after gun shows,” said the lead author, Ellicott C. Matthay, a doctoral candidate at the University of California, Berkeley. “Also, travel to less restrictive states may threaten the effectiveness of firearm laws in California.”