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Residents living near an out-of-control warehouse blaze in Melbourne are being warned about toxic smoke spewing over the city's west.
Explosions have been heard coming from the Tottenham building, with several schools closed, and a watch and act alert issued for suburbs including Footscray, West Footscray, Yarraville, Kingsville, South Kingsville, and Sunshine because of smoke concerns.
More than 100 firefighters are at the scene and expect to battle the blaze throughout Thursday, after it broke out in the 100m by 200m Somerville Rd building about 5am.
"When crews first arrived, we had no understanding of what was in the building so we've spoken to the owner and the occupier and we believe there is some acetone and some oxy-acetylene," incident controller Ken Brown told reporters near the scene.
"There's been some other explosions that we've had. We've had some 44 gallon drums explode and fly through the air, which is a concern for our firefighters.
"Oxy-acetylene is welding equipment and acetone, the best way to describe it is nail polish remover."
People in the nearby areas are urged to close their windows and doors, turn off their air-conditioning systems and bring their pets inside.
One worker at a nearby business said he heard "a lot of explosive noises" coming from the warehouse.
"It's definitely pretty severe," Dion Amato from Leading Car Care Centre told AAP.
Another worker at a second business said she could see "a lot of black smoke" while a third said it sounded "like something is blowing up".