Police said four other people died while undergoing treatment at the Thika Level 4 Hospital
Ngoliba Police Station traffic officers who confirmed the 8.30pm incident divulged that it involved a lorry and a matatu belonging to Kinatwa Sacco that was heading to Kitui from Nairobi at the time of the accident.
On his past, Thika Traffic Base Commander Michael Lemaiyan said four other people died while undergoing treatment at the Thika Level 4 hospital while two others were in critical condition at the same facility.
They said the matatu driver swerved to avoid hitting a motorcyclist and in the process collided head-on with an oncoming lorry.
"As a result, the matatu driver and his ten passengers died on the spot," an officer at the station said as quoted by the Star.
Police said the process of identifying the victims had commenced and that the public would be briefed later.
The latest accident brings to over 170 the number of people who have lost their lives through road carnage in the month of December.
Elsewhere, seven people died on Saturday night in a grisly road accident involving a matatu and lorry at Makutano along Nakuru-Eldoret Highway.
Rift Valley Traffic Enforcement Officer Arome said the accident happened when the matatu tried to overtake before slamming head-on with an on-coming lorry.
As at December 14, the National Transport and Safety Authority (NTSA) put the death toll in this festive season at 150.