Clutha-Taieri Area Response manager Senior Sergeant Alastair Dickie said the toetoe were lit near a boat ramp by the Kaitangata Bridge Tavern about 1am on Sunday.
Fire services were called from Balclutha and Kaitangata to fight the blaze.
Ten minutes after the fire, a vehicle was stopped by police which matched the description of a red hatchback seen at the location of the fires.
A person in the vehicle was breathalysed and found to be driving while intoxicated.
Snr Sgt Dickie said the group in the car were possibly connected to the arson.
''We're definitely looking into a group of people.''
The car was seized by police, Snr Sgt Dickie said.
Forensic examination of the scene was completed by the Criminal Investigation Branch and ''items of interest'' were found.
This follows a series of unusual arson attacks in Balclutha where several chairs were taken to public locations and set alight.
The public toilets at Naish Park were also set on fire a few weeks ago and there was an incident in which a pile of old tyres were set on fire near the former video store at the corner of Gordon and James Sts.
It was unlikely the fires were connected but police were still investigating, Snr Sgt Dickie said.
They would appreciate any information, he said.
-Balclutha police (03) 418-0203, Crimestoppers 0800 555-111.
