Detective Branch of Dhaka Metropolitan Police nabbed three people including the owner of the five-storey building in the capital's Siddique Bazar area in Gulistan where a blast on Tuesday killed at least 21 people and left more than 50 injured.
The arrested were identified as the building's owners, Waidur Rahman, Matiur Rahman and one shop owner who was identified as Motaleb Mintu. They were arrested in connection with a case filed over the deadly blast.
Additional Deputy Commissioner (media) KN Niyoti Roy said we lodged an unnatural death case in the incident of the explosion on Wednesday.
However, no one was named as accused in the case statement, he added saying that the investigation is ongoing, and if anyone is found involved in the blast they will be accused in the case then.
Meanwhile, another body was recovered from the ruins of the collapsed building as rescue operations resumed for the third day on Thursday.
Shahjahan Sikder, deputy assistant director (media cell) of Fire Service and Civil Defence said the body was recovered from the basement of Cafe Queen Market at around 12:15 pm on Thursday,
Downplaying the chances of any sabotage, the DB has primarily identified accumulation of biogas or a leak from an abandoned but not fully-closed Titas gas line as two possible reasons for the explosion.
In a press briefing DB chief Harun Or Rashid said the organisation traced the history of the building and gave their observations on the matter following initial investigation.
The explosion on Tuesday originated at the Queen Sanitary Market, once known as Queen cafe.
This cafe was located on the first floor, with its kitchen made in the building's basement.
When the building was being constructed, the plan was for a 10-storey unit. By 1992, the basement and the first floor were built, the media note said.
Once the spaces in the two floors were leased, large gas lines were fed into the basement for the kitchen.
When the cafe closed, the gas lines were surrendered to Titas in writing. The remaining floors were completed in 2004.
The owner of the building was the late Haji Mohammad Rezaur Rahman. After his death in 2011, his three sons, two daughters and wife were given ownership of the building, the note added.
The DB also made a number of observations, speculating on the cause of the blast. A redacted version of some of the observations are listed below:
1. The basement of the building was supposed to have car parking, but there was once a kitchen there. Currently, a commercial establishment called "Bangladesh Sanitary" sells sanitary goods in an underground space of about 1800 square feet, which is completely surrounded by glass. The sanitary shop is cooled by two big air conditioners. There is also a big water tank there. The owners of the building are not sure where the sewage septic tank is located in the seven-storey building. It is believed that the septic tanks of these two buildings are located in the two and a half/three feet alley to the north of the building.
2. Car parking in the basement would have air ventilation. Had that been in place, there would have been no accumulation of gas and the explosion would not have happened.
3. The seven-storey building housed both commercial and residential units. Waste would have accumulated for a long time, forming biogas, which can often lead to explosions and cause extensive damage.
4. The kitchen in the basement was once supplied with gas from a large commercial line. Although the line was closed, the domestic lines for the other buildings were operational. As a result, the Titas gas may leak through the line in the basement. An explosion can occur through a spark near the accumulated gas.
5. According to the building owners, there is a narrow lane between the main damaged building and the Brac Bank building on its northern side. The septic tanks, outer portion of the AC etc are located in this lane. The blast completely damaged the side walls on this lane. Biogas explosions can cause this.
6. The building had many large ACs. If the ACs were not serviced from time to time or were faulty, those could also lead to explosions like the one that happened at the UAE visa center in Gulshan around 2-3 years ago.
The DB further said the building had round-the-clock surveillance and CCTV cameras, so sabotage was out of the question.
It said different bodies were investigating the fire and the actual reason would be known soon.
It further said the property owners had violated the building codes, putting people at risk.
