The second bomb threat in two days was discovered in a Melrose High School boys' bathroom today, the school said in a statement.
Administrators discovered the note in a first-floor bathroom about 9:30 a.m., said Superintendent Joseph Casey in a phone interview.
The note was written on the bathroom wall and included today's date, the school said.
No one was evacuated, Casey said. Shortly after a class change, administrators announced a shelter-in-place protocol, in which teachers lock themselves in their classrooms with students.
Public safety officials searched the building and cleared the threat a short time later, he said.
The note is the second in two days, and mirror's yesterday's that forced an evacuation of the high school. The messages were scrawled in separate boys' bathrooms on the first floor. Casey would not release the text of today's note. Yesterday's note read "bomb in school," and the day's date, police said.
No one has been arrested or detained in the threats, Casey said, but police continue to investigate both incidents.
Surveillance cameras cover part of the school, Casey said. Visitors are required to sign in and out, and state their intended business and destination at the high school.
Students' families were notified through the school's electronic reverse-911 system, Casey said. There was no disruption in learning time, according to the school.