Classes were back to normal at White Plains High School Friday, after an apparent telephone glitch caused a lockdown alert.

An alert went out around 2:30 p.m. Thursday that triggered a large police response and notified parents that police were on the scene and clearing the building.

Some parents said within seconds of receiving the alert, they stormed out of work and rushed there. They say they were especially worried because the school had just conducted a practice drill on Monday and knew they wouldn't have another one just a few days later.

Students say they were confused and scared as rumors started to go around. Junior Troanna Durbs of Ossining High School says she heard a rumor on social media that said White Plains High School had a lockdown due to weapons in the school.

MORE: Telephone glitch may have caused lockdown alert at White Plains High School

Superintendent Joseph Ricca says the district believes the false alarm was a malfunction in one of the school telephones.

The school is trying to determine whether the alert was a technical or human error.