A 10-year-old who allegedly showed a toy gun to fellow students on an Alexandria school bus was charged with brandishing a weapon, Alexandria police said.

As children were riding home from Douglas MacArthur Elementary School on Monday afternoon, the boy flashed the gun “without indicating it was fake,” and students did not know whether it was real, police said.

At least one of the students alerted her parents, who informed the school.

On Tuesday morning, police approached the boy at school and officers found a gun in his backpack, according to police.

The handgun was a replica and could not be fired, police said. The boy was charged as a juvenile with a misdemeanor.

Virginia’s charge of brandishing a weapon can be brought against a person who shows or points a gun — or something that looks like one — whether or not it is capable of firing and does so in a way that reasonably induces fear.

The gun had an orange tip, police said, which is an indicator that a gun is a replica.

The student, whom police did not name because he is a minor, was taken into custody.

Jeannie White, past president of the school’s PTA, said she had been hearing about the incident all day. Parents first heard about it from one another, she said, so many were upset that school officials hadn’t let them know about it Monday. It wasn’t mentioned at a PTA meeting Monday night, she said.

On Tuesday, school officials sent a letter home, and she talked with her children, who are third- and fourth-graders. “They were concerned and seemed to know that’s a big deal,” she said. She told them: “If this happens, you have to tell an adult. That’s not safe, and it’s scary.”

The assistant principal referred questions to a school system spokeswoman, who did not immediately return messages Tuesday afternoon.

A 7-year-old boy in Henrico County threatened other students with a loaded handgun on a school bus Monday morning, according to police. No one was injured.

Susan Svrluga contributed to this report.