NEW CASTLE — A hazardous waste plant fire has been extinguished and an evacuation order lifted.

Officials say the fire at Castle Environmental in New Castle was caused by a welding spark about 11:45 a.m. Thursday.

About 100 homes and businesses and a nursing home were evacuated, but residents were allowed to return about 6 p.m. No injuries are reported.

The fire spread to an area containing about 1,000 gallons of sulfuric acid. Officials say other potentially hazardous chemicals on the site included up to 1,000 gallons of ferric fluoride, 700 gallons of aluminum phosphate and 50 gallons of caustic acid. Those chemicals apparently weren't released or otherwise affected by the fire.