Washington ? The government issued sharp warnings on Wednesday to paintball gun users, announcing new safety measures while investigations continue into two deaths caused by canisters flying off the guns.

The Consumer Product Safety Commission said both deaths occurred after brass valves unscrewed from the pressurized carbon dioxide canisters on the guns, which turned the canisters into projectiles.

In June 2003, a 15-year-old boy from Washington state died after the canister he was removing struck him in the head, the commission said. In February, a California mother of two was instantly killed by a canister that propelled off a gun someone was disassembling nearby.

“Make sure the brass or nickel-plated canister valve is securely attached to the canister, rotates with the canister and does not unscrew from the canister,” the commission advised.

Spokesman Eric Criss said officials did not issue a warning after the first death because not enough information was available at the time to know the cause.

Criss said the investigations should be concluded in a few months. A product could be recalled if problems are traced to a single manufacturer. The government could also call for voluntary or mandatory regulations for all manufacturers.

Bob McGuire, president of the Tennessee-based American Paintball League, said he hoped the new warnings would encourage people to become better educated on how to safely remove the canisters, which is necessary to store the guns or refill them.

McGuire said they had been aware of a “twist-off possibility” for some time but that the odds of such occurrences were remote, especially when qualified professionals were handling the guns. He said he knew of other instances of canisters flying off but only when inexperienced people tried to remove them.

The commission also advised:

l The canister assembly should unscrew from the paintball gun in about three or four full turns. If you finish the fourth full turn and the canister is not unscrewed from the gun, stop! Take it to a professional.

l Some people have used paint or nail polish to mark the valve and canister so they can see that they rotate together while being removed.

Robert Scott, owner of Twisted Paintball in Modesto, Calif., manufactures and sells paintball equipment. The Consumer Product Safety Commission warned Wednesday that canisters flying off the guns can cause injury or even death. Two people have died in such incidents in the last year.