People have been urged to avoid TATA Steelworks after a "huge explosion" in Port Talbot caused a fire to break out.
Residents reported hearing three loud bangs at the steelworks in South Wales shortly after 3.30am on Friday morning.
TATA said there were no serious injuries and all fires are "under control", although two people are believed to have suffered minor injuries.
The National Air Police Service confirmed a helicopter had been scrambled to the scene.
It said: "Attended large series of explosions at @TataSteelEurope #PortTalbot.
"Tata has now confirmed there are no serious injuries and all employees have been accounted for. All fires now under control. Excellent multi agency response from @swpolice @SWFireandRescue @SWPPortTalbot."
Resident Damian Healey told Sky News he felt a "strange compression" in the air and it sounded "as though a jet were about to pass".