Aug. 4—Alaska workplace safety officers are investigating a "localized flash fire" that injured three people at a ConocoPhillips facility in the North Slope oil fields Friday.

The flash fire occurred at about 2:30 p.m. at the Alpine Central Facility, the oil company said in a statement from Rebecca Boys, a spokeswoman.

"Work was immediately stopped in the area," ConocoPhillips said. "The injured parties received initial care at the Alpine Medical Clinic and were then flown to an Anchorage hospital for further assessment and treatment."

The Occupational Safety and Health Administration says flash fires are caused by a "diffuse fuel," such as gas vapors, liquid or dust.

One individual was released from the hospital as of Saturday, ConocoPhillips said. The other two remained in the hospital in stable condition, the company said.

The Alaska Occupational Safety and Health office is investigating the incident, said Adam Weinert, a spokesperson with the state Department of Labor and Workforce Development, in an email Monday.

ConocoPhillips said it is conducting an investigation to determine the cause of the incident.

"Our primary concern is for the safety and well-being of personnel who have been affected by this incident," the company said. "The company is providing, and will continue to provide, support and assistance to affected personnel."