The three, all employees at the plant, were taken to Scunthorpe General Hospital with “radiated” burns.
A Tata spokesman said: “We had a fire in the power station at our Scunthorpe plant at 2:00am today which led to three employees being hurt, all of whom have now been released from hospital.
“Our on-site emergency fire and rescue services arrived at the incident two minutes after the alarm was raised.”
The firm added: “A full investigation has been launched to establish the causes of today’s incident. Steel production was not affected by the fire.”