Three trucks were set alight on the R76 between Steynsburg and Kroonstad on Thursday night.
Police spokesperson Captain Stephen Thakeng told News24 on Friday morning that police are investigating cases of malicious damage to property and public violence.
"We suspect the violent protests in Kroonstad [on Thursday] spilled over to Steynsrus at about 21:00 on Thursday night. That's when three trucks were burnt. We are monitoring the situation."
Thakeng said no one has been injured in the incident and no arrests have been made.
According to Thakeng, the incident can be attributed to general "unrest" in the area. "Steynsrus also falls under the Makhado Municipality, like Kroonstad."
On Thursday, more than 60 people were arrested after Post Office and municipal vehicles were torched during more protests on Thursday, this time in Maokeng and Phomolong in Kroonstad, Free State police said.
Thakeng said that a concerned group in Maokeng, Kroonstad, who were unhappy about service delivery and high unemployment rates, had started blocking streets with burning tyres from around 6:00.
A Post Office in Phomolong and vehicles belonging to the Moqhaka municipality were also burnt.
Thakeng said police officers from Bloemfontein, Parys, Sasolburg and Welkom had arrested more than 60 people and that they would be charged with public violence.
"The situation is tense, but [Public Order Police] members continue to maintain law and order," said Thakeng.