Miscreants set fire to the Sylhet zonal office of Grameen Bank in the Shahjalal Upashahar area of Sylhet city early Sunday.
Md Abul Hossain, manager of the zonal office, said a group of unidentified miscreants arrived carrying fuel in plastic bags around 2:45am and set fire to the northern side of the building before targeting its eastern side.
At one stage, they also set fire to his car kept in the garage, he said.
A bank employee noticed the fire and informed the Fire Service and police.
However, bank officials and employees managed to bring the fire under control before firefighters and police reached the scene.
Abul Hossain said several important documents were destroyed in the fire, while his vehicle was also damaged.
Officer-in-Charge of Shahporan Police Station Ferdous Ahmed said police were investigating the incident seriously.