A freight train derailed while crossing an overpass west of Baltimore, spilling tons of coal on top of two 19-year-old women who were sitting on the bridge and killing them, police said.

The accident also crushed nearby cars and damaged telecommunications lines in the area, affecting data connections as far away as Guantanamo Bay, Cuba, where a pretrial hearing for five men accused of plotting the Sept. 11 attacks was delayed by a day as a result.

The derailment occurred just after midnight as a CSX Corp train was headed east through Ellicott City, about 12 miles (20 km) west of Baltimore, Howard County Police said in a statement.

Police discovered the dead women during their early-morning investigation of the accident, the cause of which remains unknown. The National Transportation Safety Board has taken over the investigation.

The two women, identified as Ellicott City residents Elizabeth Nass and Rose Mayr, apparently were sitting on a ledge of the bridge over Ellicott City's Main Street when the derailment occurred, police said

The police statement said the women had their backs to the train when it passed a few feet from them.

"For an unknown reason, the train derailed, causing open cars filled with coal to tip over," the statement said. "Both Nass and Mayr were buried under the coal as it dumped from the train cars."

Tweets Before Derailment

The two had been sending Twitter messages shortly before the accident and police said they are aware of photos posted to Twitter that appear to have been sent from them on the bridge.

A tweet from Nass's account, @LizNassty, sent shortly before the accident reads: "Drinking on top of the Ellicott City sign with @r0se_petals."

One photo sent from Nass's account showed two sets of bare feet dangling over a darkened street, with the caption "Levitating." A second depicts a street illuminated by street and traffic lights and captioned: "Looking down on old ec," an apparent abbreviation for Ellicott City.

According to their Facebook pages, Nass was a student at Virginia's James Madison University and Mayr attended the University of Delaware. They graduated together from Ellicott City's Mount Hebron High School in 2010, their Facebook pages indicate.

Twenty-one of the train's 80 cars derailed, police said. Operators of the train's two locomotives were unharmed.

"Many of those train cars fell onto automobiles, literally fell onto automobiles with the coal, so you have massive piles of coal and heavy train cars on top of automobiles," Howard County Executive Ken Ulman told NBC News.

Phone company Verizon Communications said the accident knocked out service along its lines through the area, which included some to government servers that were needed for lawyers preparing for a pretrial hearing for the five men being held at the Guantanamo Bay U.S. Naval Base, some 1,300 miles (2,090 km) away.

Hearings had been scheduled to begin on Wednesday for the alleged mastermind of the hijacked plane attacks, Khalid Sheikh Mohammed, and four co-defendants facing death penalty charges of mass murder, terrorism and conspiring with al Qaeda.

The derailment knocked out part of the wire-and-satellite network that provides communications to the base in eastern Cuba, said Captain Robert Durand, a spokesman for the Guantanamo detention operation. That left defense lawyers and prosecutors at the base temporarily unable to access email and electronic legal files.

CSX, which is the second-largest U.S. railroad by both revenue and stock market capitalization, said the accident did not significantly affected rail traffic in the region. (Reuters)