LA SALLE, Ill. — An investigation is still underway into the cause of a possible explosion and fire at a chemical plant in La Salle.

After the fire began just after 9 a.m. at Carus Chemical, located at 1500 8th Street, officials sent an emergency alert urging people who live in the city’s third and fourth wards to shelter in place.

As of about 5 p.m., the city lifted the shelter in place.

According to police, an oxidizer was released in the area following the incident. Officials are warning residents not to touch the substance.

A representative for Carus Chemical said it appears potassium permanganate was released during the fire and it’s not toxic.

If it is on a residence or near it, citizens can deactivate it, police said. In order to deactivate it, mix equal parts water and vinegar.

A firefighter suffered minor injuries and was treated and released. No workers at the plant or civilians were injured.

The fire started in the shipping area of the plant during regular operations, according to a press release posted on the company’s website. The cause of the fire is still under investigation.

A resident who showed up to Wednesday afternoon’s press conference asked officials what they are supposed to do.

“I’m really confused at what we’re supposed to be doing, he said. “The city can’t just listen to these guys. Did they test the stuff? Did they sample my yard?”

Residents with questions can call a new hotline set up at 815-224-6206.

Many agencies were on the scene Wednesday, including the Environmental Protection Agency, U.S. Coast Guard to check water runoff, the department of natural resources, the Occupational Health and Safety Administration and others.

The EPA said it is taking real-time samples but did not have anything to report as of Wednesday’s afternoon press conference.

According to the company’s website, the family-owned manufacturer was founded in 1915 and sells supplies, products, equipment and services for water treatment, wastewater, air purification and soil remediation.