MENDON, Mo. (KETK) — Jennifer Homendy, Chair of the National Transportation Safety Board, held a press conference Tuesday afternoon addressing the train derailment that occurred in Mendon, Missouri on Monday.

On Monday, Amtrak train four was travelling eastbound from Los Angeles to Chicago when, at around 12:43 p.m., it collided with the rear end of an MS Contracting truck, derailing the train entirely. Homendy said that the truck had been transporting aggregate to an Army corps of engineers project, just north of the crossing.

On the other hand, the train consisted of two locomotives in total, with six coach cars, a cafe car and a baggage car. All eight cars derailed when the train struck the truck.

Homendy said that Tuesday is their first full day on scene and are still in the process of investigating the accident and will be evaluating the circumstances leading up to the derailment, such as downloading the event recorder, which will give information on when the engineer blew the horn, how fast the train was going, the brake application (whether it was full-service or emergency), downloading footage from the forward-facing cameras, downloading data from the wayside and signal systems, and conducting interviews of the 12 crew members that were on-board.

Two members from the Transportation Disaster Assistance Team will be working with the families of the victims by going to the hospitals where they were taken, as well as by going to the Family Assistance Center in Columbia to work with the Red Cross. Homendy declined to comment on the number of fatalities and injuries from the derailment, saying that she has heard too many different numbers and is not comfortable giving a final estimate.

She added that there were two Boy Scout troops on board the train at the time it derailed and that they helped to provide assistance in the wake of the crash.

Homendy said that this was a “passive” railroad crossing, meaning that there was only a stop sign and a crossbuck, but no arms, warning lights, or bells, which she specified are indicators of an “active” crossing. She said that about half of railroad crossings in the U.S. and in the state of Missouri are passive.