Firefighters are battling a blaze at a major oil refinery.
Flames and clouds of thick black smoke could be seen at Stanlow Oil Refinery, Ellesmere Port, Cheshire, in images posted online.
All staff at the site have been evacuated and are accounted for, Cheshire Fire Service said.
The force, which was called at 2.16pm, believes the blaze to be at a manufacturing building inside the plant.
The refinery employs more than 900 staff and an additional 500 on-site contractors, and supplies 16% of all UK road transport fuels, according to operator Essar Oil UK.
Six fire engines are attending the scene in Oil Site Road.
He added: “I looked over to Stanlow and there was an aggressive fire and lots of black smoke.”
The fire has not disrupted the plant’s operations, a spokeswoman for Essar Oil UK said.
She said: “Earlier this afternoon a fire occurred at the SHOP chemical plant. Both the site emergency services and Cheshire County Fire Service are in attendance to deal with the incident.
“All personnel have been accounted for. Refinery operations at Stanlow remain unaffected.”
As of 3.30pm the force said the fire is confined to the site and crews are using a ground monitor and handheld monitor to extinguish pockets of flame.
Firefighters worked with on-site staff to deal with the unfolding emergency.
Stanlow has a team of 25 full-time staff to allow for immediate action to prevent potential catastrophes.
Stanlow produces 4.4 billion litres of diesel and three billion litres of petrol annually, according to Essar Oil UK.