SAN BERNARDINO (CBSLA) — The mother of a 12-year-old boy who was accidentally shot and killed by his twin brother at their San Bernardino home Monday night has been arrested.

Gabriela Keeton. (San Bernardino Police Department)

Police were called to the 900 block of East Central Avenue at about 7:30 p.m. Monday on the report of a shooting. Arriving officers found a 12-year-old boy suffering from a gunshot wound, according to the San Bernardino Police Department.

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The child was rushed to a local hospital, where he was pronounced dead. The boy’s name has not been released.

A police spokesperson told CBS2 the two brothers were playing with an unloaded and unsecured gun in the master bedroom of the home with ammunition nearby. At some point, the gun was loaded and one of the brothers pretended to shoot the other when the gun went off, police said. It is being considered an accident.

The mother of the children, 45-year-old Gabriela Keeton, was later contacted at the scene and was taken into custody on child endangerment charges. She is being held on $100,000 bail and is scheduled to make her first court appearance Thursday.

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The boys’ father was not home when the shooting occurred, police said. At the time, he happened to be hospitalized with an undisclosed medical condition.

Sean Anderson, who works a few blocks from the home, wondered why the boys were even handling the firearm.

“They know that’s a no-no, they know it’s bad,” he said. “They know an adult is supposed to hold it or carry it if there is any danger, you know.”

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The police department reminds gun owners that firearms should be locked, secured and out of reach of children.