Two youths smoking in Kulim Park appear to be responsible for causing a scrub fire about 40m long.
Firefighters were called to the blaze which was on the bank alongside the rail tracks about 3.15pm yesterday.
Senior Station Officer Phil Price said the fire was about 40m long and 5m wide when they first arrived although they had it under control quickly.
Some of the scrub was burnt, as was part of a fence, but not a lot of damage was done, he said.
Police Constable Aidan Crossman said it appeared a couple of youths having a cigarette had accidentally started the fire.