April 28, 2016 12:24 PM EDT

Fatal incidents involving toddlers and guns, including a deadly shooting this week in Milwaukee, are far more common than you might think.

The latest victim was Patrice Price, a 26-year-old Milwaukee mother, who was killed when her 2-year-old son fired a handgun he’d found in the backseat of a car. Officials say the .40-caliber gun apparently slid out from underneath the driver’s seat as Price drove her boyfriend’s car, according to the Milwaukee Journal-Sentinel. The toddler then picked up the gun and fired it, hitting his mother in the back.

The boy was the 77th child to fire a gun accidentally and harm someone in the U.S. so far this year, according to Everytown for Gun Safety, a gun control advocacy group. That number includes children age 17 and younger.

Four other young children ages 2 to 3 from across the U.S. joined Everytown’s list this week; they all fatally shot themselves after getting their hands on guns, the New York Times reports.

Read more: Toddlers Shoot Someone Every Week in the U.S.

Price’s death this week echoed a similar incident in Florida, where Jamie Gilt, a pro-gun activist, was shot by her 4-year-old son from the back seat of her car in March after the child found a handgun that had been stashed under a seat.

Last year, according to the Washington Post, 13 toddlers age 3 or younger accidentally killed themselves with a gun, 18 injured themselves, 10 injured others, and two killed other people. Most of the incidents involved unsecured handguns found by toddlers in purses and closets and underneath car seats.

Contact us at letters@time.com.

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