At least four people were injured in an industrial accident Saturday morning at the Cherry Point Refinery near Seattle, Washington. Three of the injured were hospitalized, including one person requiring advanced life support and two others needing basic life support, according to local officials.

Witnesses reported hearing an explosion around 10:20 a.m., prompting an evacuation of refinery employees. Emergency responders transported the injured workers to a nearby hospital, and company representatives said the incident was contained with no risk to surrounding communities.

Officials noted a discrepancy between initial reports on the number of people hurt, and the cause of the incident remains under investigation. All other employees have been accounted for as authorities continue to assess the situation.