Officials grounded an Air India flight to Kolkata at the Delhi airport on Wednesday after a bomb threat, PTI reported quoting an official. All 248 passengers and 11 crew members have been de-boarded.

A bomb threat assessment committee, the Central Industrial Security Force, a bomb disposal squad and canine units were called in to search the aircraft after Mumbai airport officials received a call from an individual threatening to attack the flight, according to PTI.

However, The Times of India reported that the Air India office at the Delhi airport received the threatening call. “As per the standard operating procedure for a security drill, the baggage loaded on the plane was offloaded for checks,” an Air India official told the newspaper. “This process took about two hours. Later, security agencies asked AI to make passengers alight from the plane as it needed to be taken to a remote bay for thorough checks.”

PTI quoted an unidentified a senior official as saying that the “flight has been isolated, and anti-sabotage checks are in progress at the Indira Gandhi International Airport”.

An Air India spokesperson told The Times of India that the airline had arranged for another aircraft to fly the passengers to Kolkata”.