An alleged hijacker was shot dead in a military operation at Chittagong airport in Bangladesh on Sunday evening after a Biman Bangladesh flight from Dhaka to Dubai made an emergency landing and five crewmembers and all the 142 passengers were evacuated.

“The hijack attempt was not part of an organised terror attack. Preliminary investigations revealed the gunman was mentally unstable,” a senior intelligence official said over phone from Shah Amanat International Airport in Chittagong.

However, for around three hours, the shaken security establishment was on edge in a country that has remained vulnerable to the threat of organised terror.

Reuters reported that the purported hijacker told the crew he had a personal issue with his wife. He apparently wanted to speak to Prime Minister Sheikh Hasina who was in Chittagong on Sunday for a government programme. Hasina had returned to Dhaka around an hour before the hijack attempt became public.

“We didn’t have the chance to negotiate. Our commandos had to act swiftly. He was initially injured and later died,” Major General Motiur Rahman, the general officer commanding of Chittagong, said.

Maj. Gen. Rahman, who led the operation, said the hijacker appeared to be in his mid-twenties and was holding an object that resembled a pistol.

Sources in Bangladesh said that by around 7pm, all the passengers and the crewmembers had been evacuated through the four emergency exits. Unconfirmed reports said one crewmember was kept back as a hostage.

Around one-and-a-half hours before the evacuation, the flight had made an emergency landing at Chittagong airport after the armed hijacker on board BG-147 took out the pistol-like object and tried to enter the cockpit.

The flight was midway between Dhaka and Chittagong (it flies to Dubail via the Bangladesh port city), said a senior counter-terrorism official. Some sources said the hijacker had told the crew that he was carrying explosives and would blow up the plane if his demand was not met.

“The crew informed the pilot through signals that a hijacker was on board, which prompted the pilot to lock the cockpit and then he made a quick descent after informing the air traffic control in Dhaka and Chittagong…. The emergency exits were thrown open and all passengers and most crewmembers rushed out,” said the source.

By then the navy commandos, the quick response force and a batch of trainees undergoing a counter-terrorism course in the Chittagong division had surrounded the aircraft.

Sources said that Major General Rahman tried to negotiate with the gunman, who had been detained by 7.25pm. By around 8pm, news trickled out that the operation was over and the hijacker had been killed in a quick commando sweep.

Within an hour, the airport was thrown open and take-off and landing began at the airport in Chittagong, the second biggest city in Bangladesh.

Some sources in the security establishment said Sunday’s incident shook them up. “We have to investigate how the man could board the aircraft in Dhaka with a gun or something that looked like a gun. This means the security at Hazrat Shah Jalal airport in Dhaka is not yet fool-proof,” said the source.

Passengers have to go through two rounds of security checks before boarding in Dhaka.

Bangladesh has seen the rise of fundamentalist forces in the last few years and organised Islamist terrorist activity made a menacing debut in capital Dhaka in July 2016 when an upscale café was attacked and 22 people, including several foreigners, were killed.

“The moment I learnt about the attempted hijack, the terror attack on Holy Artisan Café came to my mind…. As our Prime Minister Sheikh Hasina was in Chittagong on Sunday, the concern was more,” said an officer involved in counter-terrorism in Bangladesh.