A Lucknow-Delhi IndiGo flight carrying around 180 passengers was delayed on Friday after a bomb threat triggered a security response just before its scheduled departure.Delhi-bound IndiGo flight at Lucknow receives bomb threat before takeoff; security checks underway. (HT Photo)Authorities later found that the threat was a hoax, but the aircraft remained grounded while mandatory security procedures were carried out. The flight was scheduled to take off from Lucknow for Delhi at 10.45 am, news agency PTI reported.The crew of the aircraft received information about a possible bomb threat on board shortly before departure, sources told PTI. Following the alert, the aircraft was held back at the apron instead of proceeding for takeoff.Also read | ‘Challenging cost environment’: IndiGo pauses services to Hong Kong, Shanghai and 4 othersSecurity personnel immediately began inspecting the aircraft and surrounding areas as part of precautionary measures to ensure the safety of passengers and crew.Tissue paper with 'bomb' written on it triggered panicThe scare began after a tissue paper carrying the word "bomb" was discovered inside one of the aircraft's lavatories, sources told news agency PTI. The note prompted security agencies to initiate a full inspection of the aircraft.Also read | Bomb threat written with lipstick forces IndiGo plane from Dibrugarh to Kolkata to make emergency landingHowever, officials later determined that the threat was a hoax.No explosive or harmful substance foundDuring the security checks, officials did not find any bomb or other harmful substance on the aircraft.An official said that no explosive material was recovered during the inspection and that further legal and security procedures were underway. Reportedly, the flight had not yet taken off.(With inputs from PTI)