The accident occurred near Beltara village.
Three persons were killed and six others injured when a bus ferrying people to Prime Minister Narendra Modi's public rally in Raipur, rammed into a stationary truck in Chhattisgarh's Bilaspur district on Friday, police said.
The accident occurred near Beltara village when the bus with around 40 people on board was heading to Raipur from Ambikapur, Bilaspur Superintendent of Police Santosh Singh said.
Prima facie, the bus driver could not clearly see the stationary truck parked on the roadside due to heavy rainfall, as a result of which the bus rammed into it from the rear side, he said.
"Three people died in the accident while six others sustained injuries, two of them critically," he said.
The dead were identified as Sajan (30), Rukdev (45), both natives of Surajpur district, and bus driver Akram Raza (28), a resident of Balrampur district, he said.
Of the injured, the condition of two - Lilu Gupta, who is BJP's Latori unit mandal president in Surajpur and Vishambhar Yadav, the party's mandal general secretary in Surajpur, is said to be critical and they have been shifted to a private hospital in Bilaspur, he said.
Four other injured were admitted to Chhattisgarh Institute of Medical Sciences (CIMS) Bilspur, he said.
Investigation into the incident is underway, Singh said.
The PM's rally is scheduled to be held at Science College ground in Raipur.
Chief Minister Bhupesh Baghel expressed grief over the incident and announced an ex-gratia of Rs 4 lakh to the family of each victim, an official said.
"I announce an assistance of Rs 4 lakh to the kin members of each of the deceased in the accident with the bus which was heading to attend the public meeting of the Honorable Prime Minister," Baghel tweeted.
"Instructions have been given to the administration to provide better treatment to the injured. We all stand with their families during this difficult time," he added.