A semi fire shut down traffic on Illinois Route 394 for about four hours early Tuesday in south suburban Glenwood. The truck, hauling deoxidizer, was traveling south about 2 a.m. on I-394 near Glenwood Lansing Road when the tractor went up in flames, according to Illinois State Police. The driver disconnected the vehicle from the tractor and drove a safe distance away to call authorities, state police said. The cause of the blaze was unknown early Tuesday, and it was extinguished in about an hour, police said. No one was injured.