LAFAYETTE, La. (AP) — Thousands of people remained evacuated from their homes Sunday as hazardous material workers cleaned up hydrochloric acid that spilled when six train cars derailed a day earlier.

Saturday's derailment spread a toxic cloud over the city. Five people, including two railroad workers, were sent to a hospital and treated after complaining of skin and eye irritation, State Police Trooper David Anderson said.

Anderson said he couldn't estimate how long the cleanup and evacuation would take. Hazardous materials specialists have to work cautiously because the acid is so dangerous.

An estimated 10,000 gallons spilled, forming a yellowish pool.

By late Sunday, more than half of the acid had been removed, state police said. All six rail cars were restored to an upright position, and some had been moved out of the 1-acre contamination site, Anderson said. "The stuff we're dealing with is bad — very bad stuff," he said.