GREENVILLE, S.C. -- A bus driver's close attention to a conversation on the bus and her quick thinking, alerted school officials to a potential threat Thursday.

Two female eighth-grade students and one male eighth-grade student have been suspended pending recommendations for expulsion after a gun was found in a student's possession at Hughes Middle School, according to Greenville County School District officials.

A bus driver on her morning route said she overheard a suspicious comment from a female student and called ahead to notify the school that a gun could possibly be in a book bag of a student on her bus.

According to a release from the Greenville County School District, the assistant principal and school resource officer met the student upon the bus' arrival and conducted a search of the student's bag finding a handgun and bullets.

The district, working with law enforcement, was able to determine the gun had been exchanged earlier in the week with two other students, officials said.

Two of the students, a 15-year-old boy and a 13-year-old girl, are in the custody of Department of Juvenile Justice.

Oby Lyles, a spokesperson for Greenville County School District, said that the bus driver, and the administration and school resource officer acted decisively and in accord with district policy in handling the situation.

Lyles said parents were notified through school messenger, a phone service which calls parents to alert them of problems at the school, and told them about the incident and to call the school, if they had further questions.