Chandigarh, Jan. 30 -- Three buildings, including the Punjab and Haryana secretariat in Sector 1, the UT mini secretariat in Sector 9 and the Punjab Municipal Bhawan in Sector 35, were evacuated after the administration received a bomb threat on Thursday, just a day after 30 schools received similar threats from suspected Khalistanientities. Officials said the emails were received at 9 am and the sender signed off as "Khalistan national army" while issuing threats to the Punjab chief minister. The police were informed, following which anti-sabotage teams, bomb disposal squads, fire brigade, ambulance services and PCR teams were sent. After a search, things were back to normal as nothing incriminating was found. The police reiterated their message, urging people to keep calm. On Wednesday, after 20 private and 10 government schools received such threats, their premises were evacuated. Officials of the cyber crime police station, who are probing the incident, said the emails were sent from somewhere in the United States as suggested by the details of the sender's IP address. An official familiar with the matter said the sender could be from someone who is linked to Gurpatwant Singh Pannun, a vocal Khalistani activist who is currently based in the US and known for issuing suchthreats. Officials said they would pursue the case further under the Mutual Legal Assistance Treaty. In such hoax cases, FIRs under Section 113(3) of the Bharatiya Nyaya Sanhita (BNS) can be registered, punishable with imprisonment for a term not less than five years....