A fourth person has died after Monday's Amtrak train derailment in Missouri, according to the Missouri State Highway Patrol. 

In a statement, authorities said that three of the fatalities were passengers on the train and that one had died at University Hospital. 

"Law enforcement officials working in conjunction with first responders and Amtrak officials have determined approximately 150 people were transported from the scene to 10 area hospitals for treatment of injuries that range from minor to serious in nature. Amtrak officials stated that there were approximately 275 passengers and 12 crew members aboard the train," the patrol tweeted Tuesday. 

Investigators from the National Transportation Safety Board (NTSB) arrived Tuesday at the scene. The agency said it launched a 14-member "go-team" to investigate the accident.

Missouri

A derailed Amtrak train is seen beyond a corn field Tuesday, June 28, 2022, near Mendon, Mo. (AP Photo/Charlie Riedel)

AMTRAK TRAIN CRASH: BOY SCOUT TROOPS HELP FELLOW PASSENGERS AFTER DEADLY DERAILMENT IN MISSOURI

Amtrak Police are providing security to the site, which is located near Mendon. 

The Southwest Chief train, which was carrying more than 200 people from Los Angeles to Chicago, slammed into a dump truck. Seven of the train's cars derailed at a rural railroad crossing on a gravel road. The truck was broken into pieces. 

Amtrak

A law enforcement officer inspects the scene of an Amtrak train which derailed after striking a dump truck Monday, June 27, 2022, near Mendon, Mo.  (AP Photo/Charlie Riedel)

The crossing has no lights or other signals to warn of an approaching train. 

CHICAGO-BOUND AMTRAK TRAIN DERAILS AFTER HITTING DUMP TRUCK IN MISSOURI, AT LEAST THREE DEAD

Passenger Amanda Diehl Drinkard said she heard a crash before the train fell onto its side

"We heard a big crash and then a big cloud of dirt with a horrible burning oil smell," she told Fox News. "In slow motion the car fell off the rail to the right side. People from across the aisle were falling on top of us. Everyone stayed relatively calm and we managed to push everyone out the top through a broken out window. There were helpful people waiting at the bottom to help down from the car."

Derailment

Workers inspect the scene of an Amtrak train which derailed after striking a dump truck Monday, June 27, 2022, near Mendon, Mo.  (AP Photo/Charlie Riedel)

Passengers included 16 youths and eight adults from two Boy Scout troops who were traveling home to Appleton, Wisconsin. Fox News has learned that the troops assisted fellow passengers in getting them to safety and provided first aid.

NTSB Chairwoman Jennifer Homendy, who is serving as a spokesperson on the scene, said it was too early to speculate on why the truck was on the tracks and that trains won't run there for "a matter of days" as evidence is gathered.

Homendy is expected to hold a media briefing on the derailment.

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Fox News' Lawrence Richard, Garrett Tenney, Louis Casiano and The Associated Press contributed to this report.