The force of the impact "saw the truck cleaved and flung from the railway line," Emergency services spokesman Jeff Wicks told the Johannesburg Mail & Guardian.
Information about the accident was sketchy, Wicks said.
Sandile Simelane, a representative of Transnet Freight Rail, said the train did not derail and the tracks weren't damaged.
There were no cross bars at the crossing where the accident occurred, but Simelane said it had adequate signage, the Mail and Guardian reported.
"We have adequate signage at all our level crossings and normally as a train approaches a level crossing, within a kilometer or two [about a half-mile to a mile], it starts blowing a horn to warn people," he said.