Portugal's Prime Minister Luís Montenegro has called a furcular train crash that killed 16 people as "one of the biggest human tragedies of our recent history,"
BBC reports.
Lisbon's 140-year-old Glória funicular, which is popular with tourists, derailed and crashed into a building at around 18:15 local time (17:15 GMT) on Wednesday.
More than 20 others were injured, five of whom were in a serious condition, the prime minister added.
The head of the Portuguese capital's public transport operator, Carris, said all funiculars in the capital were now being inspected and that it had launched an independent investigation into the incident.
A day of mourning is being observed across Portugal on Thursday.
Footage shared on social media showed the crumpled yellow funicular overturned on the cobblestone street and people running from the area as smoke filled the air.
Several passengers trapped in the wreckage had to be freed by emergency responders, local authorities said.
Officials in Lisbon had initially put the death toll at 17, however that number was later revised down to 16 after they discovered a person who died in hospital overnight had been counted twice.
Among the victims was André Jorge Gonçalves Marques, who worked as a break guard on the funicular.
Carris described him as a "dedicated, kind and happy professional, always willing to contribute to the greater good".
Another victim has been named as former volleyball referee Pedro Manuel Alves Trindade. The Portuguese volleyball federation said it was "deeply saddened by the tragedy".
Officials have not indicated what may have caused the crash, but eyewitness reports suggested that the braking system on the cable-hauled funicular failed, sending it hurtling down the steep street.
A witness told Portuguese TV channel SIC that the funicular, which can carry around 40 people, "hit a building with brutal force and collapsed like a cardboard box; it had no brakes".
It is not known how many passengers were on board when the crash happened.
Portuguese newspaper Observador reported that a cable came loose along the railway's route, causing it to lose control and collide with a nearby building.
One witness told Observador that the vehicle was "out of control, without brakes".
"We all started running away because we thought [the carriage] was going to hit the one below," said Teresa d'Avó.