The loss of at least 22 lives in Tuesday's explosion at Siddikbazar in Gulistan area is the result of sheer greed and negligence of the owners of the building and the shop in its basement, found primary investigation of the police.

As per the Rajuk-approved design, the basement was supposed to be used as car parking.

But the building owners, without complying with the building code, rented it out to a trader who enclosed the entire 1,800-square-foot basement with glass, leaving no space for air passage, said police.

The proprietor of the shop named "Bangladesh Sanitary" had installed two heavy-duty ACs but those were not serviced since 2010, said DMP's Additional Commissioner Harun Or Rashid.

"It was the responsibility of the building owners to use the basement for car parking. There was no air ventilation system there and those who rented the basement never raised any questions," he said at a press briefing at DMP Media Centre yesterday.

"Their negligence caused so many deaths and injuries. So, the building owners and the shop owner cannot avoid responsibility."

The additional commissioner at the briefing disclosed the arrest of two building owners, Wahidur Rahman, 46, and his brother Matiur Rahman, 36, and proprietor of Bangladesh Sanitary Abdul Motaleb Mintu.

They were held under section 54 of the Code of Criminal Procedure, which allows police to arrest anyone without warrants.

A case over so many people's deaths and injuries for their negligence would also be filed anytime, said Mashiur Rahman, deputy commissioner of DB's Lalbagh division.

Meanwhile, fire service officials recovered a body from the site around 12:15pm yesterday.

The deceased was Mehedi Hasan Swapan, a manager of the shop in the basement, claimed his brother-in-law Abdus Sattar Babul.

After recovering the body, fire service officials said there were no more bodies trapped in the rubble of the Siddikbazar building.

"It was the responsibility of the building owners to use the basement for car parking. There was no air ventilation system there and those who rented the basement never raised any questions."

— DMP's Additional Commissioner Harun Or Rashid

"We have been conducting the rescue operation since the morning. So far, we came to know there are no missing persons. There is no other body inside the building," Md Akhtaruzzaman, assistant director (Dhaka) of Fire Service and Civil Defence, told reporters on the spot.

Besides, another victim of the Siddikbazar tragedy died at the Sheikh Hasina National Institute of Burn and Plastic Surgery.

Yasin Arafat, who was on life support with 55 percent burns, breathed his last around 8:00pm, Samanta Lal Sen, chief coordinator of the institute, told The Daily Star.

Arafat, 26, of Noakhali's Begumganj, used to live with his uncle in Moghbazar, and worked at the Bangladesh Sanitary.

Eight others undergoing treatment at the burn institute are in critical condition.

The death toll from the blast now rose to 22.

The incident left over 100 injured and 29 of them are now undergoing treatment at Dhaka Medical College Hospital and Sheikh Hasina National Institute of Burn and Plastic Surgery.

POLICE FINDINGS

The explosion took place in the basement around 4:45pm on Tuesday and ripped through the seven-storey building in Siddikbazar, a major commercial area in the capital.

The top four floors of the seven-storey building, known as Queen Sanitary Market, on North-South Road were for residential use while the rest for commercial.

Police said Rajdhani Unnayan Kartripakkha (Rajuk), the public agency responsible for coordinating urban development in Dhaka, approved the plan for a 10-storey building in 1992. 

Haji Mohammad Rezaur Rahman, the father of arrested Rahman brothers, first constructed the basement and ground floor.

He then started an eatery called Café Queen on the ground floor with a kitchen in the basement. In 2004, he constructed six more floors.

This kitchen used to get commercial gas supply from Titas Gas Transmission and Distribution Company Limited. The line was surrendered to Titas in writing after the café was closed.

But the gas connections to different floors of the building remained operational. So the accumulation of gas from any leakage was possible and just a spark could lead to an explosion, police said.

After the closure of the café, the owner initially rented the basement to be used as a warehouse and later it was rented out to the Bangladesh Sanitary owner.

Rezaur Rahman died in 2011, and his three sons, two daughters and wife are the current owners.

According to the DB findings, the septic tank of the building is seemingly beneath a narrow lane -- not more than three feet wide -- between the Queen Sanitary Market and an adjacent five-storey building.

Outdoor units of heavy-duty ACs of the shops in the market faced that lane. None of those ACs were serviced since 2010. They did not clean the septic tank of the building ever.

Had there been a car parking in the basement, there would have been an air ventilation system in place and such an explosion might not have happened, they said.

Mentioning some other possible reasons for the explosion, police also said as the septic tank was not cleaned for a long time and it is possible that biogas was deposited and caused the explosion.

There were five shops on the ground floor while the first floor housed two clothing shops and a sanitary shop. If the ACs in those were not serviced regularly or had any faults, that also could have caused the blast. 

Harun Or Rashid said, "We talked to the present owners of the building who do not even know where the building's septic tank is located.

"Our investigation will continue taking everything into consideration."