The explosion occurred on Thursday morning at the refinery of the New American Oil (NAO) company, news agency Telam reported, adding that around 90 firefighters and Civil Defense personnel managed to control the flames after several hours of fighting.
According to the news agency, one of the main crude oil tanks exploded.
"The prosecutor's office is working, examinations are being carried out and an investigation is underway into the causes of the fire," Deputy Secretary of Civil Defense and Citizen Protection of Neuquen Martin Giusti told a briefing, as quoted by the news agency.
After the explosion, oil and gas unions of the Argentine provinces of Rio Negro, Neuquen, and La Pampa launched a strike "because of the disregard for life and safety" of the workers, the news agency added.