At least two people “sustained fatal injuries” after a leak at a chemical plant in La Porte, in the US state of Texas, company officials said.

Four others sustained burns during the incident at the LyondellBasell facility in the La Porte Complex near the city of Houston on Tuesday night, company spokesperson Chevalier Gray said in a statement.

LyondellBasell is one of the world’s largest plastics, chemicals and refining companies.

The incident involved an acetic acid leak, the spokesperson said. The Harris County Fire Marshal’s Office later confirmed dozens more were injured.

LA PORTE, Texas (KTRK) -- Two people are dead after a chemical incident at the LyondellBasell plant in La Porte, city https://t.co/6Q0eubY8G2

— Rusty Surette (@KBTXRusty) July 28, 2021

Harris County Fire Marshal Laurie Christensen said at a news conference one person was air-lifted to a hospital and one was sent by ambulance.

Five others were treated at the scene and dozens were being monitored for symptoms that could include difficulty breathing and swallowing and irritants or burns to the skin.

The company said it was working closely with responders to confirm all employees were accounted for.

“Sometimes the terminology in these situations when there’s a leak, you think of something pouring out. A leak could also be something exploded off the top and the chemical came out. So once we get into the investigation, we’ll be able to specifically detail that out,” Christensen said.

Heartbroken to hear of the two fatalities at the Lyondell Basell facility in La Porte. Our county and other first responder agencies are working to support the other workers impacted and to verify that the incident is contained. Grateful to all responders. https://t.co/4ei2IFew9d

— Lina Hidalgo (@LinaHidalgoTX) July 28, 2021

Harris County Judge Lina Hidalgo issued a statement on Twitter saying she was “heartbroken to hear of the two fatalities”.

Company spokesperson Gray said: “The county and other first responder agencies are working to support the other workers impacted and to verify that air monitoring demonstrated no levels of concern for the community.”

A statement issued by La Porte EMS said there were no other protective actions being recommended for the La Porte community at this time.