Firefighters are tackling a large blaze at a building used for storing chemicals.
West Yorkshire Fire and Rescue Service was called out at about 2.34am and said 15 firefighting pumps are at the incident in Albion Way in Leeds and residents are being asked to keep windows and doors closed.
Police said the fire had taken hold at a building used by packaging firm Tradepak.
A spokesman said the "large building fire" had spread to another adjacent property and two aerial appliances and numerous specialist appliances were also at the scene.
"The matter is being treated as a large building fire by firefighters but, as with any fire producing large amounts of smoke, nearby residents are being urged to keep doors and windows closed while the smoke clears," the spokesman added.
Eyewitnesses have posted Twitter pictures of the huge blaze, which has sent thick black plumes of smoke high into the air.
The Armley Gyratory road was closed for some hours but later re-opened but other streets around the site on the industrial estate itself remain closed.