Portugal was reeling Thursday morning in the wake of an unprecedented disaster in the heart of its capital city. Sixteen people were killed late Wednesday afternoon when one of Lisbon's trademark electric streetcars — the Elevador da Gloria funicular — careened off its tracks and slammed into a building.

The funicular, a type of tram usually set on a permanent angle to run up and down a hill or mountain, has carried people about 270 yards up and down a hill in central Lisbon for more than a century. It's hugely popular with tourists, and The Associated Press said about half of the 21 people injured in the crash were foreign visitors.

Officials haven't released the names of the victims, but rescuers have said there were foreign nationals among those killed. The State Department on Thursday confirmed that a U.S. citizen was among those killed in the derailment. "Our staff in Lisbon and here in the United States are working tirelessly to provide consular assistance to the victim and their family," a spokesperson told CBS News in a statement.

The Reuters news agency said emergency services had confirmed three other funiculars in Lisbon were undergoing additional safety checks Thursday following the deadly crash.