A "Roman candle" in the sky led firefighters to a blaze at a Westport joinery factory last night.
A hopper at TRT Builders in Cobden Street caught fire about 5.30pm.
"It was just like a big Roman candle, standing out on its own," said Westport fire chief Alan Kennedy.
Firefighters had to open a vent inside the hopper to quell the blaze, he said.
"But it took a while because we had to wash all of the shavings out of the bin onto the ground to put it out; It could have been a lot worse than it was."
He understood a stone or a knot in timber had created a spark which landed in wood shavings.
The fire gutted the hopper but the main factory about 30 metres away was undamaged.
Mr Kennedy said firefighters spent about three hours at the scene, then returned a couple of times last night to check the fire hadn't reignited.
TRT manager John Blair said the blaze could have been much worse.
"We're very lucky the wind was going towards the river - it blew the flames away. It could have got into the wood racks, it just took one building."
He agreed with Mr Kennedy that a rogue spark was probably to blame.
"We are pretty sure it's a spark that got into one of the machines and sucked up into the system. It's just bad luck."
He had no idea of the cost of the damage. The loss of the hopper - which stored wood and shavings from the factory and elsewhere - would have little impact on operations. "We will have to get some sort of system, whether it's bags or whatever," Mr Blair said.
The hopper had originally come from TRT's Romilly Street factory when the company moved to Cobden Street in 1999.