Police said the three "notorious" traffickers had died after being shot during an anti-trafficking raid in the southern coastal town of Teknaf in the Cox's Bazar district, close to the border with Myanmar.
The traffickers were suspected of smuggling thousands of Bangladeshi and Myanmar nationals across rough seas to Malaysia and Thailand.
The raid followed the discovery this month of migrant graves and a network of secret jungle camps by people- smugglers in Thailand's deep south.
He added that one of them, 55-year-old Dholu Hossain, had been responsible for smuggling more than 1,000 Bangladeshis, "many of whom are now believed to have died in the sea or of starvation".
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"He used to send 50 people, mostly poor locals, per shipment in locally made wooden fishing trawlers, taking Taka 20,000 (USD 255) from each person," he told AFP, adding that Dholu had been arrested several times but released on bail.
Teknaf police chief Ataur Rahman said the three men had operated human trafficking networks at home and in Thailand and Malaysia, where many were later held hostage in remote jungle hideouts.
Thousands of young men have gone missing from coastal villages in southern Bangladesh in recent years.
Locals there reacted with anger after Thai authorities exhumed more than 30 bodies, all believed to be from Bangladesh and Myanmar, from two graves this month.
Bangladeshi police have said they have rescued more than 3,000 people from Cox's Bazar and Chittagong city from the hands of traffickers over the past five years.