ADAMS TWP — Mars High School students started their school day Friday morning at the middle school, while bomb-sniffing dogs and police checked the high school for a bomb. A note found Thursday afternoon stated that a bomb would go off at 9:28 a.m. Friday, said the district’s director of communications, Josh Schwoebel. He said the note caused the district to cancel all activities Thursday and delay the start of classes for two hours Friday morning to accommodate the search by the Allegheny County Bomb Squad. Classes started at 10 a.m. Students attending club meetings, sports practices and other activities were shooed off the high school property after dismissal on Thursday when officials discovered the school’s second bomb threat note in three weeks. Students who drive to school were instructed not to arrive until 10 a.m. Friday. High school teachers were told to report to the middle school at their regular start time. Police officers from Adams and Middlesex townships and Mars blocked all entrances to the school Friday morning as bomb-sniffing dogs and a variety of officers swept the building and grounds. The scene was identical to the one that played out on Feb. 11 at the school, when a female student left a note in the bathroom of the girls’ locker room that read “Good luck with the bomb. Have fun Mars High.” That student was arrested in the days following the incident when her parents brought her to the Adams Township Police Department to confess to the crime. The police did not disclose exactly what the note said, where it was found or if they have any suspects. Schwoebel said security at the high school was heightened Friday because of the threat. “(Mars School District) strives to remain proactive in the protection of its students, faculty and staff members,” Superintendent William Pettigrew said in an online letter to parents.