BEAUMONT -- A fire Wednesday at an Exxon Mobil refinery in Southeast Texas left 12 contract workers injured, officials said.Beaumont Fire Department spokesman Brad Penisson said three of those injured were critically burned. Other workers suffered burns and broken bones.Exxon Mobil spokeswoman Rachael L. Moore said the fire happened around 10:30 a.m. in a process unit that was down for maintenance. Such units are involved in processing crude oil into refined products.The company says the fire was quickly brought under control and has been extinguished. Penisson said refinery personnel put out the fire before Beaumont fire department units arrived.Exxon Mobil said all employees and contractors working in the area of the process unit have been accounted for."We sincerely regret this has happened and will conduct a complete investigation to determine the cause of the incident," Moore said in a statement.Seven of the injured were taken to Baptist Hospital in Beaumont, said spokeswoman Mary Poole.Three of those workers who had suffered burns were later transferred to the University of Texas Medical Branch at Galveston, with one in critical condition and the other two in stable condition. The four workers who remained at Baptist Hospital were in stable condition and might be released later Wednesday, Poole said.ExxonMobil did not immediately know the conditions of the five other injured workers, who were taken to Christus Hospital-St. Elizabeth in Beaumont.The refinery is part of a 2,400-acre complex near downtown Beaumont, which is about 90 miles northeast of Houston. The complex includes a refinery, a chemical plant and a lube plant. The refinery processes 365,000 barrels of crude oil per day and produces 2.8 billion gallons of gasoline annually.