Two workers died and another was injured after a fire broke out over the weekend at the biggest domestic refinery owned and operated by Mexico's state oil company Pemex, a company official said on Monday.

The fire broke out on Saturday at the Salina Cruz refinery in southern Oaxaca state, plant manager Arturo Recio told reporters, explaining that a storm caused the drains filled with oily waste to overflow into the walkways inside the complex.

A 21-year-old woman and 26-year-old man working for Pemex contractors died, and another man was hospitalized, Recio said.

He said that work at the main distillation plant and a gasoline plant was paused to avoid further damage, but that none of the other units were affected. Recio added that cleaning and repairs were underway.

The refinery's crude oil processing capacity stands at 330,000 barrels per day, and it currently runs at about 70% of its capacity. The refinery was operating normally after the fire, a Pemex source said.

Local media reported that the incident started in the refinery's internal courtyards, near some major plants, and that the fire was put out by company workers and civil protection.