After last week's U.S. school shooting, Ken Larson and his wife have decided to buy their son an armoured backpack, just to be safe — even though the one-year-old won't be in school for a few more years. Larson already owns an armoured backpack himself.

"My son's life is invaluable," said Larson, 41. "If I can get him a backpack for $200 that makes him safer, I don't even have to think about that."

Meanwhile, firearms enthusiasts across the U.S. are stocking up on semi-automatic rifles in anticipation of tighter gun control measures as President Barack Obama demands "real action, right now."

A spike in gun sales is common after a mass shooting, but the latest rampage has generated record sales in some states, particularly of assault weapons similar to the AR-15 rifle the gunman used Friday to kill 26 people at the school, including 20 children just six and seven years old. He first killed his mother at home in her bed, and finally killed himself at the school as emergency responders closed in.

Colorado set a single-day record for gun background check requests the day after the shootings, while Nevada saw more checks in the two days that followed than any other weekend this year. Records were also set in Tennessee, California and Virginia, among others.

Some gun shop owners stopped selling the remaining stock of their assault weapons, anticipating only more interest and value after Obama on Wednesday instructed his administration to create concrete proposals to reduce gun violence that he could give to Congress by January.

Rush of customers

Robert Akers, a South Dakota gun seller who specializes in military-style weapons, said the rush of customers had transformed his Rapid Fire Firearms store into a "madhouse" and that he's not actively selling the guns and has turned off his phone.

"The price is only going to go up higher," he said.

There was also an unusual increase in sales for armoured backpacks designed to shield children caught in shootings, according to three companies that make them.

The armour inserts fit into the back panel of a child's backpack and sell for up to $400 US, depending on the retailer. The armour is designed to stop bullets from handguns, not assault weapons like the one used in Friday's shooting.

Still, the manufacturers and some parents say that while they don't guarantee children won't be killed, they could be useful as shields.

Some experts, however, say sending children to school in armoured backpacks is not a healthy response to fear. Anne Marie Albano, psychiatry director at Columbia University's Clinic for Anxiety and Related Disorders, said parents should convey calmness, not anxiety.

"This is not serving to keep children safe," she said. "This is serving to increase their fear and their suspicion of their peers."

At the Amendment II store in Salt Lake City, sales of children's backpacks and armoured inserts have increased, with 200 purchase requests Wednesday alone.

Rick Brand, the chief operating officer of Amendment II, shoots a 9 mm pistol into a children's backpack, left, fitted with an anti-ballistic insert during a demonstration at a gun range, Rick Brand, the chief operating officer of Amendment II, shoots a 9 mm pistol into a children's backpack, left, fitted with an anti-ballistic insert during a demonstration at a gun range, (Rick Bowmer/Associated Press)

"The incident last week highlights the need to protect our children," said co-owner Derek Williams. "We didn't get in this business to do this. But the fact is that our armour can help children just as it can help soldiers."

Kerry Clark, president of Texas-based Backpackshield.com, began making the backpacks after the deadly mass shooting at Virginia Tech in 2007. Clark said he sold 15 backpacks Wednesday. Prior to Friday's shooting, he said, the company would sometimes go an entire month and just sell one.

"It's the busiest I've seen it in my life," he said.

Bullet Blocker, a company that sells the backpack armour, declined to provide sales numbers but noted that recent sales were substantially greater than normal.

Sales of assault weapons also were on the rise.

Austin Cook, general manager of Hoover Tactical Firearms in Alabama, said the spike in sales has been so intense that federal background checks that typically take five minutes or less are now taking up to an hour.

Cook said about 50 people were waiting in line for his store to open the morning after the shootings, and that he's since sold nearly all of his assault weapons. Now, he's trying to find more distributors.

"I can't keep them in the store," Cook said.

Dick's Sporting Goods has said it was suspending sales of modern rifles nationwide because of the shooting.

Aaron Byrd, co-owner of Patriot Shooting Sports in North Carolina, is sold out of AR-15 rifles, ammo for those types of guns and high-capacity magazines.

"A lot of people have been coming in looking to purchase semiautomatic rifles. They're worried that the government's going to ban semiautomatic rifles and high-capacity magazines, so they've been coming in looking for those," he said.

Byrd added, "I think it is a knee-jerk reaction by both parties — both the government and the citizens."