The Stanlow Oil Refinery has been evacuated after witnesses say they saw a 'fireball explosion' at the huge Cheshire plant.
Fire crews are currently battling against a blaze in one of the manufacturing buildings at the Ellesmere Port facility.
The fire started around 2pm and all staff have been accounted for and evacuated.
Fire engines from Powey Lane, Chester, Widnes and Northwich and two from Ellesmere Port are all battling the flames.
Crews are currently working with on site firefighters to extinguish the fire.
Phil Owen was waiting for the ferry at Seacombe when he looked down the Mersey and saw what looked like an explosion.