Contractors were draining and cleaning three diesel tanks at the back of the Batley factory on Wednesday morning when a spark caused one to catch fire.
Eyewitnesses described how a burst of flames was seen coming from the site, followed by clouds of thick smoke.
Aneela Zaman, who lives opposite the yard, said she saw people running from the factory, screaming.
One man was rushed to Pinderfields Hospital with burns to his legs, and five other people were taken to Dewsbury and District Hospital as a precaution.
Keep checking this website for updates, and video footage of the aftermath of the explosion.
Check out this week’s Batley and Birstall News, out tomorrow, for the full story.