While seven of them were killed on the spot, two persons succumbed to their injuries on the way to the hospital, they said.
"We are in the process of ascertaining their identity. Several persons are critical and they have been admitted at the Ariyalur Government Hospital," Ziaul Haque, Superintendent of Police, Ariyalur District told PTI.
The accident occurred at 4.20 PM on the State highway to Senthurai from here.
The accident appears to have occurred due to an error in the judgement of one of the drivers, police said adding, top officials are on the spot coordinating rescue efforts.