Police said the accident happened at 8am on the 86km peg.
Chief Superintendent Oliver Mandipaka said police were still verifying the identities of the deceased before informing their next of kin.
He said that a Toyota Hiace carrying what police suspect to have been 29 passengers developed a mechanical fault before veering off the road and slamming into a gum tree.
Sixteen people died on the spot while two others died on admission at Mvurwi Hospital.
“Preliminary investigations show that the vehicle’s right rear wheel stud broke while the vehicle was in motion,” Mandipaka said.
“The wheel then fell off before the vehicle veered to the right and drove for 70 to 100m and hit into a gum tree.”
The accident comes two weeks after 13 people from Zimbabwe died when the bus they were travelling crashed in South Africa.
