Seventeen people have died after the Portuguese capital of Lisbon's Gloria funicular railway car, which is popular with tourists, derailed and crashed.
The death toll rose from 15 to 17 after two of the 23 people injured in the crash died.
The dead were all adults, Margarida Castro Martins, head of Lisbon's Civil Protection Agency, told reporters on Thursday.
She did not provide their names or nationalities, saying that their families would be informed first.
"It's a tragic day for our city ... Lisbon is in mourning, it is a tragic, tragic incident," Carlos Moedas, mayor of the Portuguese capital, told reporters.
Footage from the site showed the yellow tram-like funicular, which carries people up and down a steep hillside in Lisbon, destroyed, and emergency workers pulling people out of the wreckage on Thursday morning AEST.
Police investigators were inspecting the site and the prosecutor general's office said it would open a formal investigation, as is customary in public transport accidents.
The Department of Foreign Affairs and Trade (DFAT) said on Thursday that Australian officials were making urgent enquiries following the crash.
"The Australian Government offers its deepest sympathies to those affected," a DFAT spokesperson said in a statement.
"We are not aware of any Australians who have been killed or seriously injured. We are providing consular assistance to one individual."
Portugal is observing a national day of mourning on Thursday after the capital's worst disaster in recent history.
Portuguese President Marcelo Rebelo de Sousa lamented the tragic accident in a statement, expressing hope that authorities would soon determine the cause of the crash.
The line, which opened in 1885, connects Lisbon's downtown area near the Restauradores Square with the Bairro Alto (Upper Quarter), famous for its vibrant nightlife.
A formal investigation will be opened into the cause of the crash. Source: AAP / EPA / Miguel A Lopes
Its two cars are attached to opposite ends of a haulage cable, with traction provided by electric motors on both cars.
The 19th-century streetcar is one of Lisbon's big tourist attractions and is usually packed with foreigners at this time of year for its short and picturesque trip up and down one of the city's steep hills.
Portugal, and Lisbon in particular, have experienced a tourism boom over the past decade, with visitors crowding the popular downtown area during the summer months.
