NORRIS CITY, Ill. (AP) - A southern Illinois sheriff says four people were injured after an oil-field explosion perhaps sparked by a welding job.

White County Sheriff Doug Maier says injuries to three victims burned during the blast Tuesday near Norris City were “very serious.” They were hospitalized. A spokeswoman for El Dorado’s Ferrell Hospital, Heather Morris, says one of those victims was transferred to another hospital with burns over half of his body.

The fourth victim was treated at the El Dorado hospital and released.

The sheriff says a preliminary investigation shows welders were working on a tank when something ignited. Norris City firefighters quickly doused the blaze.

State fire investigators are assisting in the probe.

Norris City is a 1,000-resident village near the Illinois-Indiana state line, about 50 miles west of Evansville, Ind.