A man who gave his girlfriend's 14-year-old son a gun was arrested after the boy's 7-year-old brother brought it to school, authorities said Saturday.

Shamel Miller, 23, was arrested on charges of reckless endangerment, acting in a manner injurious to a child and criminal possession of a weapon.

The telephone rang busy at Miller's Brooklyn address Saturday morning, and police did not know whether he was represented by a lawyer.

The boys' mother, Andrea Clarke, 35, told investigators Miller gave her teenage son the .38-caliber revolver "for protection at school," according to police. She told her boyfriend to get the gun out of her house, but her son kept it and tried hiding it under a mattress, police said.

The younger boy, a second-grader, found the unloaded gun and took it to Public School 63 in Queens on Thursday, terrifying schoolmates by playing show-and-tell with the weapon, according to police. A teacher confiscated the revolver after another student told her about it.

Clarke, a city traffic enforcement agent, was arraigned Friday on charges of reckless endangerment and endangering the welfare of a child. She was ordered held on $15,000 bail. Her attorney did not respond to a telephone message Friday.

The older boy also was arrested and charged as a juvenile in a family court case.

The 7-year-old has not been arrested or charged in the case.