The first phase of Bishwa Ijtema, the largest Islamic congregation after Hajj, started yesterday on the bank of the Turag river in Tongi.
With the presence of thousands of devotees from home and abroad, the phase began with the delivery of religious sermons after Fajr prayers, and will end tomorrow with Akheri Munajat (final prayer).
The second phase will be held from January 17 to 19.
The three-day congregation includes delivery of sermons, prayers for spiritual adulation and welfare of Muslim Ummah, and recitation from the holy Quran and Hadith.
Meanwhile, four of the devotees have died due to old age complications in last two days, said Emdad Hossain, officer-in-charge of Tongi Police Station.
They are Shahidul Islam of Noagaon, Khoka Miah of Sirajganj, Mohammad Ali of Chattogram, and Yakub Sikdar of Gopalganj.
Their Namaz-e-Janaza was held at the Ijtema ground after Juma prayers led by Maulana Quari Zobayer, imam of Kakrail Mosque.
During the prayers, vehicular movement on Dhaka-Mymensingh highway and other adjoining roads came to a halt for a few hours.
To ensure security during the programmes, law enforcers have taken up a multi-layered security system.
Uniformed and plain-clothed members of police, Rab and intelligence agencies have been deployed in the area, said Gazipur Police Commissioner Anowar Hossain.
Over 400 closed-circuit television cameras at the 20 entries to the ground, 25 watch towers, and 11 checkpoints have been set up to monitor the area, he said.
A central and eight sub-control rooms have also been set up for the proper monitoring of the whole security system, he added.
Gazipur Deputy Commissioner SM Tariqul Islam said uninterrupted electricity and water supply were being provided in the area during the congregation.
He said the authorities were also providing health care facilities to the devotees participating in the Ijtema.