Police spokesperson Wayne Bvudzijena was quoted by state television as saying that the truck had crossed into the oncoming lane and side-swiped Tsvangirai's vehicle.
"The 4x4 Toyota Landcruiser is understood to have overturned and rolled thrice," the report said.
Two others hurt
Tsvangirai's spokesperson James Maridadi told reporters at the hospital in Harare that the accident happened at 16:00, and that two other people were in the car.
He declined to confirm Susan Tsvangirai's death, but another party official said on condition of anonymity that she died at the scene.
"Mrs Tsvangirai died on the spot... but the details are still sketchy," the party official said.
"The driver of the truck appeared to be sleeping," an MDC minister told AFP.
Tsvangirai was taken to a private hospital, where he was in a stable condition a senior party official said after visiting him....
Dirk Kotze of the University of South Africa said with the cause of the accident still unclear, any perception of foul play could have serious consequences.
"If it was just an accident and there was no foul play...then it will not have direct political consequences for Zimbabwe," he told AFP in Johannesburg.
"But it will bring a major crisis if there is any suggestion that it was not just an accident."...