A freight train hauling hazardous materials derailed in southwestern Wisconsin on Thursday, sending cars into the Mississippi river.

The derailment took place near the village of De Soto in Crawford County at about 12:15 p.m. local time. Though all crew members have been accounted for, there were at least four employees who were injured, the BNSF Railway train operator told CNN.

Emergency Crews Working to Keep Multiple Hazards Contained

Multiple BNSF train cars were involved in the derailment, with two of them ending up in the Mississippi River. However, both of those cars ran ashore.

BNSF, various EMS crews, and the Wisconsin DNR are on the scene working on the safe removal of the cars and hazardous materials, according to WKBT.

BNSF spokesperson Lena Kent said in a statement to WXOW, "Two of the three locomotives and an unknown number of cars carrying freight of all kinds were involved. Two containers went into the Mississippi River; neither contained hazardous materials.

"Some of the containers derailed on shore contained paint and lithium-ion batteries. Boom is being placed in the impacted area. The volumes involved don't pose a risk to the river or the communities. Local first responders are on-site and BNSF will work with local and state agencies as appropriate," she said.

The train was also carrying oxygen, another potentially hazardous material, which can cause an explosion if not properly maintained.

Some of the emergency crews involved with working to keep the incident under control include fire departments from Ferryville and De Soto, the Wisconsin DNR and Crawford County Hazmat team.

Booms have been deployed to contain any spills from the engines and rail cars, according to WXOW.

“It was reported to us that there were hazardous materials on the train itself, but it is not believed to be a concern to the public or the responders at this time as those cars were contained,” Marc Myhre, a Crawford County emergency management specialist said during a news conference, according to CNN.

Hazmat crews were still at the site as of Thursday evening as a precaution, since lithium-ion batteries can have a chemical reaction if they come into contact with water, Vernon County emergency management director Brandon Larson commented.

The Crawford County Sheriff's office is not calling for evacuations and doesn't feel that evacuations will be needed, according to WXOW.

Cause of Derailment Still Under Investigation

As of Thursday night, Crawford County emergency management director Jim Hackett said that investigators "still don't have a determination of what caused this train derailment."

U.S. Rep. Derrick Van Orden (WI-03), who represents the district where the derailment took place, released a statement saying his office is in the process of reaching out to state officials, BNSF, and the Federal Emergency Management Agency to "get answers on what occurred," according to CNN.

In addition, representatives from his office are in route to the site of the derailment and will, "continue to monitor the situation and determine next steps," Van Orden's statement read.

Earlier this month there was a train derailment in Pittsburgh, Pennsylvania involving a Norfolk Southern train. This same company also had a train derail in February in East Palestine, Ohio, according to ABC News.

There was also a derailment in Florida in March involving hazardous materials being hauled by Seminole Gulf Railway, according to Washington Digest.