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Five workers missing in explosion at Oklahoma drilling site - sheriff's office

(Adds Patterson comment, details on fire, background on previous fire)

HOUSTON, Jan 22 (Reuters) - Five workers remained missing after a gas explosion occurred on Monday at a drilling site in eastern Oklahoma, according to Pittsburg County Emergency Management Department.

The blast occurred at around 9 a.m. (10 a.m. Eastern) near Quinton, Oklahoma, about 146 miles from Oklahoma City. Five of the 22 workers at the site are still listed as missing, said Kevin Enloe, director of the Emergency Management Department. No one was transported to local hospitals, he added.

The explosion occurred during oil and gas drilling using a rig provided by Patterson-UTI Energy Inc, Enloe said.

The fire was still burning on site.

Patterson-UTI confirmed in a statement that some of its employees were missing after the fire.

This is the second fire at an Oklahoma oil and gas well site in less than a year. A gas explosion occurred at a Trinity Resources well in the same area in February 2017, injuring a worker.

Boots & Coots, Halliburton’s well control and prevention service, had been called in to control and fire and well, and two people from the state's energy regulator Oklahoma Corporation Commission were also on the scene. (Reporting by Bryan Sims, additional reporting by Liz Hampton; Editing by Chizu Nomiyama and Andrew Hay)