Background checks for people wanting to buy guns in Colorado jumped more than 41 percent after Friday morning’s shooting at an Aurora movie theater, and firearms instructors say they’re also seeing increased interest in the training required for a concealed-carry permit.

“It’s been insane,” Jake Meyers, an employee at Rocky Mountain Guns and Ammo in Parker, said Monday.

When he arrived at work Friday morning — just hours after a gunman killed 12 and injured 58 others at the Century Aurora 16 theater — there already were 15 to 20 people waiting outside the store, Meyers said.

He called Monday “probably the busiest Monday all year” and said the basic firearms classes that he and the store’s owner teach are booked solid for the next three weeks, something that hadn’t happened all year.

“A lot of it is people saying, ‘I didn’t think I needed a gun, but now I do,’ ” Meyers said. “When it happens in your backyard, people start reassessing — ‘Hey, I go to the movies.’ “

Between Friday and Sunday, the Colorado Bureau of Investigation approved background checks for 2,887 people who wanted to purchase a firearm — a 43 percent increase over the previous Friday through Sunday and a 39 percent jump over those same days on the first weekend of July.

The biggest spike was on Friday, when there were 1,216 checks, a 43 percent increase over the average number for the previous two Fridays.

The checks are required before anyone may legally purchase a gun in Colorado. Because some purchasers may have bought more than one gun or decided against their purchase, the actual number bought may have been different from 2,887.

Such increases aren’t unusual in the wake of mass shootings.

After a gunman in Tucson killed six people and injured others, including Congresswoman Gabrielle Giffords, in 2010, background checks in Arizona jumped 60 percent over the same date one year earlier, according to the FBI.

A similar increase occurred in Virginia after the shootings at Virginia Tech University in 2007.

Dion Studinski, who teaches a course required for people to apply for a concealed-carry permit, said his class for Saturday at Firing-Line gun store and indoor shooting range in Aurora is overbooked.

“We’ve definitely had an increase,” he said.

Tom Mauser, a gun-control advocate whose son Daniel was killed at Columbine High School in 1999, said he wasn’t surprised by the numbers.

“To me that’s just symbolic of the fear that drives (people),” he said.

State Rep. Rhonda Fields, D-Aurora, said she understands what people are thinking when they walk into a gun shop. But she hopes buying a gun isn’t the only response people have.

She would also like to see Congress reinstate an assault-weapons ban, and she said Colorado should look into other measures that could prevent tragedies like Friday’s shooting.

“I think that’s what the conversation needs to be,” she said. “I don’t think that to be preventative, we need to provide or have more guns.”

Sara Burnett: 303-954-1661, sburnett@denverpost.com or twitter.com/sara_burnett