"We don't often see this type of incident. The columns were very weak and this is really very unfortunate," a probe body member told The Daily Star yesterday.

Members of the committee supposed to submit its report within a week visited the spot yesterday.

"We just witnessed the demolishing work. We would test the soil, materials and rod to find out the reasons behind the incident," said Mehedi Ali Khan, chief engineer of Dhaka City Corporation (DCC).

"Before conducting the tests we cannot make any comment," Khan added.

He said the committee members checked the southern part of the building and found no problem. "We are only demolishing the northern part which subsided," added the chief engineer.

Khan said families, who used to live beside the six-storey building and returned home following their evacuation just after the incident, can stay without any risk.

Meanwhile, the construction firm of the building, Atik Construction, has already drawn Tk 45 lakh, which is 15 percent of the total bill, Tk 2.90 crore. Mayor Sadeque Hossain Khoka also admitted the fact.

According to a DCC source, the firm, allegedly owned by a leader of Jatiyatabadi Jubo Dal, BNP's youth front, was one of the syndicated contractors of the DCC that used to control all tenders of the city corporation.

Khoka, the city father, said the contractor might have political affiliation but he is not a prominent leader.

The two-part building was designed for 60 families. The northern part of the building was meant for 30 families. The construction work of the building was completed recently and was supposed to have the first families move in on June 3.