Hours before the counting for West Bengal assembly polls, four Trinamool workers were on Thursday injured when some unidentified men hurled bombs at the party office in Titagarh area of North 24 Parganas district.
Additional Superintendent of Police Dhrubojyoti Dey said unidentified men hurled crude bombs at the party office, which was then teeming with Trinamool members and supporters.
Four Trinamool Congress activists were injured in the attack at Tata Gate bus stop, about 20 km away from Kolkata, but the attackers' identity remained unclear, Dey said.
President of North 24 Parganas unit of Trinamool Congress, Nirmal Ghosh, claimed one of the injured persons was chairman of party-run Titagarh Municipality, Prashanta Choudhury.
Agitated Trinamool supporters blocked the vital B T Road after the incident demanding arrest of the attackers. The injured were admitted to B N Bose Hospital and R G Kar Hospital in Kolkata.