Five buses were torched at bus company Putco's Nancefield depot in Johannesburg on Sunday night.
Putco spokesperson Lindokuhle Xulu said the buses, belonging to contractors, were set alight by a group of people on Sunday night.
"Our security team reported identifying a number of people at the Nancefield depot. It's reported that those people shot at the security before fleeing the scene and leaving the buses burning," added Xulu.
He said staff and security guards "bravely" moved some buses to safety, which minimised the damage.
Firefighters from the City of Johannesburg Emergency Services tended to the blaze.
"We can confirm that we were called to the Nancefield bus depot last night (Sunday). We managed to put out fires on around five buses and contained the fire," said Johannesburg Emergency Management Services spokesperson Robert Mulaudzi.
The attack on security personnel at the depot and the cause of the fire were under investigation, Johannesburg Metropolitan Police Department spokesperson Xolani Fihla told News24.