The injured are Alamgir Hossain, 35, an assistant sub-inspector of Rab-2, Md Nurunnabi, 45, a contractor and his brother-in-law Md Abdul Aziz, 26.

Rab picked up Nasiruddin Ahmed, an accountant of Japan Garden City, Mohammadpur, in this connection.

The Rab member was admitted to Chest Diseases Hospital in Mohakhali while the other two were under treatment at the Orthopaedic Hospital in Sher-e-Bangla Nagar.

Rab and local sources said the two extortionists went to Farzana Builders and Construction at Shyamoli Ring Road where they shot Nurunnabi and Aziz. Both of them received bullets in their right hands.

Assistant Superintendent of Rab-2, Kazi Asharful Aziz told The Daily Star that two plain-clothes Rab men, who were patrolling the area, went to the spot after hearing the shots. He said one of the criminals shot Alamgir in the chest and both of them escaped riding their motorbike.

The injured contractor and local sources said extortionists demanded Tk 6 lakh from three contractors of the firm. One Azam, claiming to be the brother of a former ward commissioner, called them over telephone on Wednesday demanding the amount. The caller also threatened to kill them if they failed to deliver the money.