Locals said they heard a big sound at about 3:00am and later found around 1,200 square feet area affected by the subsidence in the morning.
They said cracks developed also in the nearby buildings after the subsidence.
The subsidence might have been occurred due to excessive use of underground water in the area or sudden rainfall after prolonged draught, said Abdus Sobhan, a councillor of Rajshahi City Corporation, quoting the experts of Public Works Department.
"I felt a sudden jerk after a big sound. I thought it was a quake," said Anwarul Iqbal, a resident of the three-storey building owned by Abul Hossain.
He said a drain and land close to the building subsided by one and a half feet.
Dwellers of a one-storey building came out of their residence in panic when they heard the sound in the night.
In another incident in Naogaon, curious people thronged Nindoin village where cold air has been whizzing out from underground at two points for the last four days.
While visiting the village yesterday morning, this correspondent found local people digging two holes at a distance of 200 yards in Malir beel. Cold air comes out of the holes.