The incident occurred after the vessel, named 'Shah Amanat', arrived at the Paturia No. 5 terminal from Rajbari's Daulatdia around 9:30 am on Wednesday, according to BIWTC spokesman Nazrul Islam Misha.
The authorities have initially learned that the vessel was loaded with 17 goods-laden trucks.
The ferry started tilting when two trucks and passengers disembarked, said Nazrul. "Half of the vessel submerged in the river near the terminal. The water is being pumped out of the ferry and rescue efforts are underway.”
Informed of the matter, two units of the Fire Service were dispatched to the scene.
Divers are currently engaged in a search operation, said Rafi Al Faruk, a Fire Service control room officer.
The cause of the incident was not immediately clear. However, Amal Bhattacharya, a passenger of the ferry, said that water started rising in the ferry as it neared the terminal. After docking at the jetty, the ferry tilted and started sinking.
The authorities suspect water poured through a leak in the bottom of the vessel, according to Shivalaya Police chief Firoz Kabir.
No casualties have been reported so far, according to Paturia River Police chief Abu Bakar Siddique.
Citing witnesses, he said, "I've heard that three trucks were swept away. The ferry was also carrying a few motorcycles and private cars."
More details will come in the course of the rescue operation, he added.
Rajbari MP Kazi Keramat Ali visited the terminal upon hearing news of the accident while en route to Dhaka.
He pointed out that the accident occurred near the wharf, indicating that the consequences could have been much worse if the vessel capsized in the middle of the river.
Shivalaya's UNO Jesmin Sultana, who was also at the terminal, said "four or five vehicles" managed to get off the ferry before it overturned.
"Then it suddenly capsized. We have learned that there was a total of 17 trucks and quite a few passengers on board. By the time the ferry started tilting, the majority of the passengers had disembarked. We haven't received any reports of casualties."
A probe panel will be constituted to look into the cause of the accident, she added.