Police are at Tata’s Welsh steelworks following reports of an explosion at the plant in the early hours.
Residents living near the Port Talbot plant spoke of hearing a “massive” blast shortly after 03:30 BST.
Images posted on social media show flames at the site and plumes of smoke. Helicopters were reported to be circling overhead.
Tata Steel said the fires at the plant are “under control” and all employees had been accounted for.
It said there had been no serious injuries.
South Wales Police said in a statement that it received “numerous calls” shortly after 03:30 “reporting an explosion”.
“At this time we believe there are just two casualties with minor injuries,” it added.
A Tata Steel spokesman said the company was working with emergency services.
He said: “We can confirm there has been an incident at our Port Talbot site.
“Emergency services have attended and are working with our on-site services.
“We will provide an update as soon as we know more.”