Amtrak said in a statement on its website that the train collided with a dump truck that was obstructing a public crossing near Mendon, Missouri on June 27 at 12:42 pm there.
According to the company, there were approximately 243 passengers and 12 crew members on the train.
Two of the people who died were aboard the train when the accident happened and the third person was in a dump truck that the train hit, spokesperson for Missouri State Highway Patrol Troop B Cpl. Justin Dunn said.
A team from The National Transportation Safety Board (NTSB) is on its way to investigate the incident. They have requested camera footage and other data from Amtrak, but the cause of the tragedy is still unknown.
Eight passenger carriages and two locomotives got derailed, according to The Independent. The passengers had to climb out upwards through the doors, as most of the carriages flipped onto their sides.
A school has been turned into a triage center for victims with minor injuries, officials said.
House Speaker Pelosi and Other Officials React
House Speaker Nancy Pelosi tweeted expressing grief over the derailment in Missouri.
“My heart goes out to all those affected by today’s horrific train derailment in Missouri,” she said. “While there are no words that can console those grieving lost loved ones, may it bring them comfort that so many Americans pray for them on this tragic day.”
Missouri governor Mike Parson said that he was saddened to hear of the Amtrak train derailment in Chariton County this afternoon. He appealed to Missourians "to join us in praying for all those impacted.”
Kansas City Mayor Quinton Lucas said that his "heart went out to all passengers", while recalling his Amtrak train trips.
(With inputs from CNN and The Independent.)