The U.S. Department of Labor's Occupational Safety and Health Administration is investigating a fire and subsequent explosion that shook a gas processing plant Thursday morning in Reeves County, approximately six miles north of Orla, OSHA officials said Friday. Two people suffered minor injuries in the blast, local authorities told NewsWest 9, and more than 200 workers were evacuated. The facility, Ramsey Natural Gas Processing Plant, is owned by Western Gas Partners, L.P. and operated by Anadarko Petroleum Corporation. The cause of the explosion has not been determined yet, Reeves County investigators said. The plant was previously fined for unrelated safety citations, federal inspection records revealed. A planned OSHA inspection in February uncovered five violations - three of which are listed as "serious violations" - that resulted in initial fines totaling more than $26,000. The citations were later settled, informally, and accompanying fines were lowered, OSHA records confirmed. According to an Anadarko spokesman, the violations were "primarily related to PSM (Process Safety Management)" and were "promptly addressed and resolved." Process safety management is an analytical tool focused on preventing releases of any substance defined as a "highly hazardous chemical." Further details about past inspection citations at the Ramsey plant were not made available. OSHA has six months, by law, to complete the ongoing investigation into Thursday morning's explosion. Diana Petterson, a Department of Labor representative, said "it is difficult to say how long [the] investigation may last." Anadarko officials and Ramsey gas plant employees expressed gratitude for the "life-saving" work of first responders who rushed to the scene. At least five law enforcement agencies from two states responded to the incident.