Four others were critically injured in the incident which took place in Kharagpurand are undergoing treatment at a hospital.
All the victims were florists by profession.
According to police, the now-deceased were loading sacks full of flowers into a pick-up van on the main road at Buromala area under Kharagpur Police Station, when suddenly a cement-laden truck ran over them.
While three persons died on sport, three others succumbed to their injuries after being shifted to a local hospital.
The condition of four others, who have been hospitalised, is stated to be extremely critical, the police said.
Soon after the accident, the locals started the initial rescue operations.
Later, the cops of the Kharagpur Police station reached the spot and shifted the bodies to a hospital for post-mortems.
The police are yet to release the identities of the dead and the injured.
Meanwhile, in a separate incident, another person was killed this morning on the national highways in Bankura district after being hit by a speeding truck.
The victim has been identified as Shanto Bhui (44).