The two women killed in a tragic train derailment in Ellicott City this week died of “compressional asphyxia,” according to autopsy results released Thursday.

View Photo Gallery: The women had been tweeting from near the tracks before the CSX train hauling coal near Ellicott City derailed. Some of the train cars fell off the 20-foot-tall bridge and onto vehicles parked beneath.

Elizabeth Conway Nass and Rose Louese Mayr, both 19, were sitting on a rail bridge late Monday night when a CSX freight train inexplicably derailed.

Howard County police released the cause of the deaths and the ruling that they were both accidents.

Elizabeth Conway Nass and Rose Mayr

Investigators have said that Nass and Mayr narrowly missed being hit by an overturned train car, but were buried under about 110 tons of coal.

As the investigation into what caused the derailment continues, funeral arrangements for both women have been made.

Funeral services for Nass are planned for Friday at the Church of the Resurrection in Ellicott City. Services for Mayr will be held Saturday at Bethany United Methodist Church in Ellicott City.