ST. GABRIEL - Officials are still investigating what caused a chemical plant in Iberville Parish to release ammonia into the air Monday morning. 

A spokesperson for the Eastman plant in St. Gabriel said the facility released the chemical shortly before 7 a.m., prompting the closure of LA 30 near the property. Personnel were able to stop the release after about 10 minutes, and the highway was reopened around 8 a.m.

Three employees at a nearby business reported being exposed to the chemical and are being evaluated, Eastman said in a statement. 

The site has since given an all-clear to resume operations.