Nexen has not indicated the cause of the explosion, or whether the victims were employees of the company.
Staff and regional first respondents were on site, the facility has been shut down and the scene was being stabilized, it added.
"There is no immediate danger to the neighboring communities or personnel still on site. Regulators have been notified," Nexen said in the statement.
A subsidiary of China’s CNOOC Limited, Nexen has experienced one of the largest land spills in North American history last July, when an emulsion leak from a pipeline covered approximately 4 acres of land.