Portuguese officials focused Thursday on establishing the causes of the crash of a Lisbon streetcar popular with tourists that killed at least 16 people and injured 21, five of them seriously.

Aerials showed the destroyed tram cart and the damage from where the car derailed from the tracks.

The downtown streetcar, which is known as Elevador da Gloria and is a major attraction for tourists packing the Portuguese capital during the summer season, came off the rails during the evening rush hour.

The crumpled wreckage was cordoned off as investigators sifted through the wreckage, took photographs and pulled up a metal cable from beneath the rails that climb one of Lisbon's steep hills.

Portugal’s attorney-general’s office said eight victims have been identified so far: five Portuguese, two South Koreans and a Swiss person. The identities of the other eight are still to be determined, it said in a statement.

“This tragedy … goes beyond our borders,” Prime Minister Luis Montenegro said at his official Carris’ CEO Pedro de Brito Bogas said during a news conference Thursday residence, calling it "one of the biggest tragedies of our recent past.” Portugal observed a national day of mourning Thursday.

The electric streetcar, also known as a funicular, is harnessed by steel cables and can carry more than 40 people. On Thursday, officials took photographs and pulled up cable from beneath the rails that climb one of the Portuguese capital’s steep hills.

Officials declined to comment on whether a faulty brake or a snapped cable may have prompted the descending streetcar to careen into a building where the steep road bends.

“The city needs answers,” Lisbon Mayor Carlos Moedas said in a televised statement, adding that talk of possible causes is “mere speculation.”