An ammonia leak occurred at a plant in Fresno, Fort Bend County, on Tuesday.
Emergency crews were sent to the Champion Technologies Inc. facility, 3130 FM 521, shortly after 11 a.m.
The plant was evacuated. Employees were allowed back inside at 11:45 a.m. and non-essential personnel were sent home early, officials said.
The plant's spokesman said the leak was not capped as of 1 p.m. and the tank's valve was damaged.
No injuries were reported and all workers were accounted for, officials said.
Fresno is located southwest of Houston and has about 19,000 residents, according to the 2010 census.