There are many types of firefighters. One distinction is between the volunteer firefighter and the professional firefighter. Another is between the urban firefighter who fights structure fires and the wildland firefighter, who fights forest fires. A distinction is often drawn between engine and truck firefighters, based on the differing capabilities of their apparatus. The increasing role of the fire service in emergency medical services has meant that many if not most firefighters are also EMTs and some are paramedics. Some specializations of firefighting include working the rescue squad, becoming a HAZMAT specialist or arson investigator, or being promoted to command positions.