A blaze at a chemical factory has caused a massive explosion spewing toxic smoke into the air. Emergency services were first alerted to the fire at a waste management business on Kurrajong Street in North St Mary’s, Western Sydney, about 10.50pm on Saturday. Footage from the scene shows explosions and fireballs shooting out from the blaze, with residents as far as Penrith claiming to have felt the shockwaves. NSW Fire and Rescue said there are concerns the blaze is being fuelled by toxic chemicals. “Stay away from the scene and close their windows, doors and vents during the emergency to avoid harmful smoke,” Fire and Rescue said. Almost 200 firefighters from across Sydney raced to the scene and are tempting to extinguish the blaze, which NSW Police said is “expected to remain active for a considerable amount of time”. “A 200m exclusion zone has been established and motorists are urged to avoid the area,” police said. The only reported injuries have minor hand injuries sustained by firefighters, but locals said they are concerned living so close to the warehouse. “I’m definitely scared, especially living very close to the fire,” one told 7NEWS. Another said it was “terrifying”, adding he “feels bad for the firefighters at the scene right now”. Fire and Rescue said the blaze was spotted as high as 150m above the factory, while a large chemical tank shot up into the air and raining “fist-sized chunks of concrete blocks” on top of firefighters. HAZMAT crews and the Environment Protection Authority have joined emergency services on the scene who will try to deal with “the subsequent chemicals being consumed in the fire”. Investigations into what caused the blaze are expected to be launched.