Unidentified armed men assaulted two security guards in the paint shop of the Tata Motors small car plant at Singur.
Five armed men sneaked into the project area at on Monday night and beat up security guards with iron rods, police said.
Alarmed by screams of the injured other
security men rushed to the site but could not nab the attackers. The injured were first taken to Singur Gramin Hospital and then shifted to Walsh Hospital at Srirampore.
No FIR has been filed by the company officials yet, they said.
Senior police officers went to the spot.