The 34-hour siege at one of the two suspected terror hideouts in Moulvibazar ended yesterday with police recovering body parts of seven to eight people, including those of four children.

Police said the militants may have "blew themselves up" to avoid arrest when SWAT and CTTC teams launched an assault codenamed "Operation Hit Back" on the den at Nasirpur in Sadar upazila around 6:00pm on Wednesday.

A bomb disposal team entered the house around 4:00pm yesterday and found seven heads and other body parts lying scattered, counter terrorism officials said. 

It's not clear how many people were inside the house, cordoned off by police around 1:30am on Wednesday, hours after the army-led operation at a Sylhet den ended that evening.

The Special Weapons and Tactics (SWAT) team was also preparing for an assault on the other suspected hideout at Moulvibazar's Borohat, some 20km from Nasirpur, today. Both the houses are owned by a Bangladeshi expatriate in England. 

Separately, police sealed off a suspected terror den in Comilla on Wednesday and an operation to take on the militants there is likely to begin today. 

Monirul Islam, chief of Counter Terrorism and Transnational Crime (CTTC) unit of Dhaka Metropolitan Police, briefed reporters about the operation around 5:00pm near the spot. 

"Judged by the decomposed condition of the bodies, it seems the militants killed themselves on Wednesday when SWAT started the raid in the evening," he said. 

"We think there were seven to eight bodies of people of different age. There were men, women and may be a couple of children. Our crime scene unit is working there. They will be able to specify [the number]."

Explaining the possible suicide, Monirul said, "It's not a new tactic. As seen in the past, when they [militants] find no way to escape, they kill themselves rather than surrender to police."

He said they were pretty sure that "Neo JMB" members were hiding there.

The body parts were sent to Moulvibazar Sadar Hospital for autopsies.

Polash Roy, resident medical officer of the hospital, told The Daily Star they primarily found the dead include four children, two women and a middle-aged man.

“We will be able to say the exact number after matching the body parts tomorrow [today],” he added.

During the raid, reporters and locals were not allowed to go near the hideout. Separately, the district administration clamped Section 144 around 2km radius of the den, prohibiting gathering of more than five people.

Monirul Islam said the counter terrorism officials used a drone to get a picture of the den and found several Improvised Explosive Devices (IEDs) fitted at the entrance and other strategic points of the house.

The explosives are similar to those seized from the Sitakunda den in Chittagong earlier this month and also the ones found with the man who blew himself up near a police checkpoint close to the Dhaka airport last Friday, he said.

The discovery of the three hideouts in Moulvibazar and Comilla came hot on the heels of the nearly five-day siege at a terror den in Sylhet, where four militants were killed.

This month saw a number of suspected militant attacks and busting of several terror dens in different parts of the country.

CTTC officials primarily thought that one of the dead is Sohel Rana, aged around 32, a top leader of “Neo JMB.”

However, there was no official confirmation yet.

The officials came to know about Sohel from two militants -- Jasim and Arjina -- arrested at a Sitakunda hideout in Chittagong on March 15.

Sohel visited Baishari village in Naikkhangchhari upazila in Bandarban several months ago from Dinajpur. There, he radicalised some people, including Jasim and Arjina, the officials added.

"OPERATION HIT BACK"

Monirul said a small team of the counterterrorism unit with the help of Moulvibazar police started working in the area on Tuesday night, tracing links to the two explosions during the army-led raid at Atia Mahal in Sylhet on Saturday night.

Four civilians and two police officers died in the twin explosions, for which Islamic State took credit.

When police cordoned off the Nasirpur den on Wednesday morning, the militants threw grenades and tried to flee, but failed.

Officials of SWAT, bomb disposal unit and other CTTC officials reached the scene on Wednesday afternoon from Dhaka.

"Considering the nature and amount of the explosives the militants had, it was decided by the higher authorities that mainly SWAT would handle the operation, while other divisions of police, Rab and firefighters would help them,” Monirul said. 

The actual offensive started on Wednesday evening. Before that, when the den was under siege, there were about 12 explosions. Before launching the operation, SWAT members repeatedly asked the militants through loudspeakers to surrender, he said.

As the SWAT men asked them to surrender, a powerful explosion took place breaking the door and glass windows of the building. The operation was postponed soon as darkness fell. The den remained cordoned off throughout the night. Launching of the operation yesterday was delayed due to bad weather.

Replying to a question, Monirul said the militants at Atia Mahal and Nasirpur dens could be related. “According to information gained from the caretaker, a family with a father-in-law lived here. But we aren't sure.”

“It seems the militants at Atia Mahal and those here are all Neo JMB men. Their ideologies are the same. It seems they used the place as a hideout.”

He also said the militants didn't seem to be locals. “They didn't leave the house much. People of the neighbourhood didn't know them. They didn't mingle with them. They didn't have jobs. The children didn't go out either. They didn't go to school. Nobody saw them.”

Before the bomb disposal team entered the house in the afternoon, explosions and continuous firing were heard after the SWAT team resumed the operation amid rough weather.

The Daily Star correspondents heard the first explosion around 11:15am and a louder one at 12:58pm.

Firing continued at regular intervals since the resumption of the offensive.

Police also fired teargas shells at the house around 1:10pm.

As rain pelted down, the special team of police entered the premises around 10:10am.

Earlier around 5:00am, the team tried to enter the premises but their operation was obstructed due to rainstorm, Mohammad Shahjalal, superintendent of police in Moulvibazar, told The Daily Star.

DAILY LIFE HAMPERED

The last two days had been difficult for locals as schools and shops were shut because of the operation.

"We, especially the children, were frightened. The restriction on free movement has also been inconvenient,” said Ramjan Ali of Nasirpur.

Sheikh Akhlish Mia, president of Boro Kapon Government Primary School managing committee, said classes were suspended in his school for security reasons.

“I didn't sell anything in the last two days. So I suffered some losses,” said Raisul Ahmed, a furniture store owner.