A watershed moment for the department, community, and Aiken County happened in the early morning of January 6, 2005, when a Norfolk Southern freight train collided head on with another railroad engine on a siding about 200 yards from Headquarters.  Approximately 80 tons of chlorine gas leaked from a ruptured tanker car within about 20 minutes.  Nine people perished within a few minutes, several hundred more were transported to hospitals for treatment, and some were permanently disabled. Within the first few hours, the department conducted searches, evacuated hundreds of residents, and fought coal fires burning in the steam plant located at the collision site.  The department managed the incident for over a week, coordinating the efforts of multiple emergency agencies, Homeland Security, and local aid organizations.  At the time, the incident was considered the worst railroad accident in US history.

The department lost Engines 33 and 35, a medical first responder vehicle, and a service truck; all were totaled by long-term exposure to high levels of chlorine gas.  Everything in Headquarters was also lost, including spare hose, protective gear, air fill system, communications equipment, and furniture.  Even the use of the building was lost for months while it was gutted, rewired, and rebuilt.

In the aftermath, two new custom engines were purchased to replace the lost apparatus.  The lost medical first responder vehicle was replaced by Truck 34, which was on order at the time of the accident.