Fruit trader Swapan Kumar and his two children -- Madhbai, 9, and Sohag, 11, -- were among the six injured in the crossfire. The other injured are Shaymal, 36, his wife Shefali Rani, 30, and son Shanta, 7.

Swapan lodged the case with Doublemooring police against eight alleged criminals of the 'Barisal Colony' slum in the city's West Madarbari area, police said.

The accused are Mohammad Shahjahan, Badal, Jasim, Jasimuddin, Lokman, Humayun Kabir, Al Amin and Mohammad Selim.

Police picked up Al Amin, 24, and Selim, 22, from the spot after the gunfight on Wednesday afternoon and sent them to the court yesterday.

According to witnesses, armed hoodlums belonging to 'Shahjahan Group' and 'Noor Group' exchanged about 20 rounds of bullets during the half-an-hour gunfight over drug peddling, establishing supremacy and extortion at Barisal Colony.

"We are trying to nab the criminals involved in the gunfight," said Mohammad Shafiquddin Chowdhury, assistant commissioner (detective branch) of Chittagong Metropolitan Police yesterday afternoon.

The two arrestees would be taken on remand and quizzed to extract information about the gangs, he said.

The slum has long been known as a 'safe haven' of notorious criminals and drug peddlers. A powerful syndicate comprising CMP-listed top-notch criminals, in collusion with a section of police, controls the slum area, police sources said.