Chandigarh, Feb. 28 -- In what was the fourth such instance for tricity schools in a month, at least 21 private and government schools in Chandigarh received bomb threat emails on Friday, leading to immediate evacuation and security deployment. The mails turned out to be a hoax and no suspicious objects were found on any of the campuses, officials later confirmed. Since January 28, public places, including schools, government buildings and hospitals, across tricity have received bomb threat mails on eight occasions (see box). On Friday, the Information Technology exam for CBSE Class 10 students was going on when the threat mails were discovered by school authorities. Among the private schools that received the mails were Shivalik Public School, Carmel Convent School, Banyan Tree School, Chitkara International School, Kundan Public School, AKSIPS-45, Vivek High School, St John's School, Gurukul Manimajra, Delhi Public School (DPS), 3BRD Air Force School, Ankur Public School (Sector 14), Ashiana Public School and DC Montessori School. Among government institutions, Government Model Senior Secondary School (GMSSS), Sector 16, GMSSS-10, GMSSS-8, GMHS Dadumajra, GMSSS-21, GMHS-41 and GMHS-48 got the mails. Police said standard security protocols were activated as soon as the information was received; and police teams, bomb disposal squads and fire services were rushed to the affected schools for search operations. A student of Chaitanya School said, "When we saw the police presence, we knew it was the same bomb threat situation again." Another student remarked: "Thank God it was the computer exam today. Had it been a difficult subject, this panic could have really impacted us." Vivek High School director HS Mamik said immediate steps were taken to ensure safety. "The younger students, aged four to five, were asked to go home as a precaution. Once the bomb squads gave clearance, students waiting for board examinations were allowed to enter and normal functioning resumed," he said. At St Kabir Public School, authorities said they remained in close coordination with the police. Honey Chitkara, principal of Chitkara International School, said precautionary measures were taken despite the school not being an examination centre. Cops, meanwhile, said a probe is on to trace the origin of the threat messages and identify those behind them....