It happened at 11:45 a.m. at the Anchor Glass Container Corp. on Griffith Street.
A company spokesman said 50 tons of liquid glass, at temperatures reaching 2800 degrees Fahrenheit, leaked from a brick furnace, damaging some surrounding equipment.
No workers were injured.
Fire officials say it took crews about an hour and a half to contain the spill. Cleanup efforts were underway and were expected to be completed by late Thursday night.
Firefighters remain on the scene, pouring water on the glass to help it cool.
According to its website, Anchor Glass makes bottles, jars, drinking glasses and similar containers and is headquartered in Tampa Florida.