Teenagers were spotted letting off fireworks then fleeing the scene as a scrub fire broke out near Waldronville yesterday afternoon, a witness says.
Five fire appliances were called to the blaze on a reserve near the Kaikorai estuary after it had been reported by passing motorists just after 3pm.
''They disappeared and then two of them walked out and the other ran like hell,'' he said.
The three young men then got into a white boy-racer type vehicle and fled the scene, and then ''I saw the flames''.
The area, which is covered in scrub and lupins, went up ''very fast''.
A Fire Service spokesman said the fire burnt through about half a hectare of reserve land between the gun club and the estuary. It came within several metres of a pile of tyres near the gun club, he said.
Rural Fire Service firefighters were at the scene last night dampening down the area.
A scene examination is expected to be made this morning.