Five devotees have died at Biswa Ijtema ground from Friday evening to Saturday morning.
Officer-in-Charge Abdul Momin of district detective branch of police said the devotees died of old age and other health complications.
He said Abdus Salam, 50, of Kapasia died of breathing difficulties around 8pm on Friday while Jahangir Alam, 65, of Badda died of old age complications around 11pm.
Natore's Kafil Uddin Mondol, 50, died of cardiac arrest around 12:45am on Saturday. Kishoreganj's Khairul Kabir, 55, and Riaz Uddin, 52, died around 9:30am.
Biswa Ijtema began on the Turag River bank at Tongi on the outskirts of the capital on Friday.
The first phase of the Ijtema will end on Sunday with the munajat.
As per schedule, the second phase of the Ijtema will begin on January 16 and will end on January 18.
The first Ijtema was held at Kakrial Mosque in Dhaka in 1946. This was followed by a congregation at Chittagong Hajji camp in 1958, then at Siddirganj in Narayanganj. Since 1965, the Bishwa Ijtema has been held at Tongi.