The Ellis County Sheriff's Office says the explosion occurred about 9:30 a.m. Thursday at a rig near Milford, about 40 miles south of Dallas.
Flames could be seen shooting into the air and some vehicles at the worksite had been burned. Billowing black smoke was seen from miles away.
Elllis County sheriff's spokeswoman Jo Ann Livingston says authorities have not received any word of injuries.
Lt. James Saulter said deputies were going door-to-door in Milford, advising people in the town of about 700 to leave.
Milford school Superintendent Don Clingenpeel (KLING'-en-peel) says all students and staff were being evacuated to the nearby town of Italy.
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