The police are confident they are closing in on the ringleaders behind the arson trucks.
This is according to Briga Athelinda Mathi, who said two more suspects have been arrested, bringing the total number to five so far.
It said one was arrested in Mpumalanga and the other in Limpopo.
On Thursday, the police announced the first breach with the arrest of two truck drivers in Mpumalanga. The third suspect was arrested in Melanie on Thursday evening.