PUTNAM COUNTY, Fla. (CBS12) — A fast-moving wildfire burning across north and central Florida has prompted a multi-agency response, including support from the St. Lucie County Fire District.

The fire, known as the Railroad Complex Fire, ignited in dry brush and timber along the rail line between Clay County and Putnam County. Investigators believe the blaze began near railroad infrastructure, where extreme heat, friction, and drought-stressed vegetation created conditions for rapid ignition and spread.

As the fire intensified earlier in the week, officials confirmed that an Amtrak train bound for New York was brought to a stop along the route when flames and heavy smoke cut off safe passage. More than 200 passengers were stranded on board for over 38 hours, with limited access to food, water, and restroom facilities while crews worked to stabilize the corridor, per previous reports.

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The statewide response quickly escalated, bringing in multiple agencies, including the St. Lucie County Fire District, which deployed a brush truck and two firefighters as part of Florida’s mutual aid system. Their assignment placed them directly into active suppression and mop-up operations on the Railroad Fire.

As of Saturday morning, officials report the fire had burned approximately 4,743 acres and reached 70% containment. Overnight, crews focused on strengthening containment lines and extinguishing interior hot spots that continue to smolder beneath the surface, according to Putnam County Fire Rescue.

Fire crews say daytime operations are now centered on “mop-up,” an intensive phase that involves digging out hidden heat pockets, reinforcing fire breaks, and patrolling for flare-ups. Despite the improved containment, authorities stress that the fire remains active and capable of reburning if conditions shift.

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Safety concerns remain a top priority. Agencies noted that mop-up operations carry some of the highest risk for firefighter injury due to fatigue, unstable ground, and concealed heat sources. Crews are conducting repeated briefings and maintaining heavy equipment support across the burn area.

Officials continue to urge the public to avoid the fire zone, warning that traffic in the area could slow response times and place both residents and firefighters at risk.