Police filed a case accusing some 50 unidentified fishermen over the alleged attack on river police by the fishing community that left six cops injured on Monday night. Md Kamruzzaman, officer-in-charge of Chandpur River Police Station, said their Assistant Sub-Inspector Saiful Islam filed the case against 50 unidentified fishermen at the police station following the attack. He, however, said no one could be arrested in this connection. Fishermen alleged that they only get a 25 kg allotment of rice from the government to survive with family members during the 22-day ban, which is too miserly against their demand. At least six cops were injured in the attack by fishermen when the law enforcers were enforcing a ban on hilsa catching in the Meghna River in Chandpur on Monday night. The government imposed a 22-day ban on catching, selling, hoarding and transporting of hilsa – from October 7 to October 28 this year– to protect safe spawning of the fish during its peak breeding period.  Read: Defying Hilsa ban: 8 fishermen get 14 days in jail each On Monday night, a team led by executive magistrates Sharmin Akhter and Zahid Hasan, went to Bishnapur union's Safarmali area in Sadar upazila to conduct the drive when a group of fishermen hurled brickbats at them, OC Quamruzzaman said. "Hasan Mia, 26, of river police was critically injured during the attack. He was taken to Chandpur General Hospital. Later, Hasan was referred to Central Police Hospital in Dhaka," he added. "Several other policemen were injured in this attack and received primary treatment at Chandpur General Hospital." On the other hand, a team of Alu Bazar police outpost conducted a drive to curb fishing during the ban period in Nilkamol area of the Meghan River on Monday afternoon. Sensing the presence of the police, some fishermen on board an engine-run trawler hit the police speedboat, which caused four fishermen to fall in the river and the loss of a shotgun of one Bashar. Md Jahirul Islam, in-charge of the police outpost, said divers from the fire service are yet to recover the gun from the river after conducting drives on Monday night and entire Tuesday. The four fishermen were rescued.  Md Kamruzzaman, superintendent of police of Chandpur Zone River Police, said they are vigilant to save mother Hilsas and none will be spared in connection with the attack on cops.