Police arrested the injured six and recovered a pipe-gun, ammunition and three knives from their possession.

The four dead were identified as Tamsu, 35, ringleader of the infamous`Tamsu bahini', Babul, Bachchu, 30, and Sohrab, 26.

Tamsu and his accomplices attacked the boat of fisherman Hossain Mia in Challir Beel at 4:00am firing gunshots to create panic at the scene, police and eyewitnesses said.

Other fishermen guarding the water-body barricaded the robbers and informed Nikli police station over cell-phone about the gang attack.

"As police rushed in, the robbers locked in a gunfight with them. Also hundreds of villagers coming out of their homes nabbed all the robbers in a combined action," says a spot account of the predawn raid.

Enraged locals beat them black and blue, leaving three dead on the spot and injuring seven. Police rescued the injured ones--Sohrab, Mohorom Ali, Yasin, Suruj, Selim, Harun and Sultan -- and took them to Nikli Health Complex. Sohrab died there.

A number of villagers were also injured in the clash. The injured villagers Polash Mia, Babul, Mishu Mia, Hossain and Anil were also admitted to the health complex.

Police said `Tamsu bahini' men were wanted in nine cases pending with Nikli, Karimganj, Kotiadi and Kishoreganj police stations.