Fairfax County police have arrested a teenager suspected of phoning in a bomb threat that closed Annandale High School for nearly three hours Friday and snarled bus transportation for 18 elementary schools.

Marco Antonio Verduo Toledo, 19, of Burke has been charged with felony threats to bomb and criminal trespass, said police spokesman Bud Walker.

Toledo is a former Annandale High student, said schools spokesman John Torre.

The threat was made in a phone call to WJLA-TV about 4:30 a.m. It led to a security sweep of the high school that involved bomb-sniffing dogs and robots and lasted nearly six hours. A suspicious backpack found on the school’s front lawn was ultimately declared not to be a threat.

Former Annandale High School student Marco Antonio Verduo Toledo, 19, was arrested for phoning in a bomb threat against the school. (Fairfax County Police Department)

Because those buses were unavailable to run their usual routes, transportation was delayed for students at 18 nearby elementary schools. It took several hours for the school system to send e-mail and phone alerts to parents.

Parents complained that the school system could have avoided the confusion and uncertainty by declaring a two-hour delay in the early morning hours.

School Board member Sandy Evans (Mason) said school system officials recognize that the situation should have been handled more smoothly.

“There’s already a lot of soul-searching about what went wrong,” Evans said. “We’re supposed to be a lot more nimble than this.”