HOUSTON -

A fifth-grade student shot a classmate with a BB gun at an elementary school, school district officials said.

Houston Independent School District officials said the incident happened at Garden Villas Elementary,  7185 Santa Fe Drive, as classes dismissed on Tuesday.

A woman who identified herself as the mother of the boy with the BB gun said her 10-year-old son had the item in his backpack over the weekend and forgot to take it out before he went to school. She said the gun went off as her son and another boy argued near a school bus.

School district officials said the victim was not seriously injured.

"I want to assure you that the safety of your children is our top priority and that this incident is being treated with the utmost seriousness," the school's principal wrote in a letter to parents. "We are reviewing the incident to determine whether any changes to our policies and procedures are needed."

The woman who identified herself as the mother of the boy with the BB gun said she accepts full responsibility for not checking her son's backpack before he went to school. She said her son feels horrible about the situation and claims that he was defending himself.