The five-member investigation committee submitted its report to Home Minister Asaduzzaman Khan on Thursday.
Wishing anonymity, a Home Ministry official said the probe body mentioned in its report that the fire ensued from the first floor of the building.
He, however, declined to elaborate further.
At least 71 people were killed and many others injured in the devastating fire that broke out at a chemical warehouse and raged through four other adjacent buildings in the city’s Chawkbazar area on January 20 night.
Of them, 67 died on the spot while the rest succumbed to their injuries at Dhaka Medical College Hospital.
The Home Ministry on February 22 formed the five-member committee, headed by additional secretary of its Security Services Division Pradip Ranjan Chakraborty, to probe the incident.
The committee was asked to submit its report within seven working days with recommendations.