Talbott Springs Elementary School in Columbia delayed dismissal Tuesday after a parent saw two teenagers exchange a BB gun near the school's playground, according to Howard County Police.
The incident resulted in a modified lockdown of the school.
Police spokeswoman Sherry Llewellyn said a parent saw a 13-year-old boy hand a 14-year-old girl what appeared to be a gun, which the girl put in her backpack.
The parent said she called out to the pair, whom she said ran away, and then called police, according to police.
Officers responded and found the teens near the school. The teens led them to a nearby trashcan, where a BB gun was found, police said.
Both teens will be charged as juveniles with disrupting school activity and other charges, Llewellyn said..
In a second email to parents, Principal Nancy Thompson said the activity was reported on the playground by vigilant parents.
"At that time, I did not feel as though it was safe to dismiss our children until the Howard County Police assured me that it was safe to dismiss," Thompson wrote.
Thompson said all students have been dismissed from the building.
This story has been updated.