Is a hazardous materials incident an accident where hazardous materials are present?

One way of describing a "hazardous materials incident" would be "an accident where hazardous materials are present." However, many people are uncomfortable with the use of the Word "accident" which implies an unplanned event that could not have been avoided. That is why the Word "incident" is used in the first place. It does not carry any implication of inevitability.