Investigators sifted through the wreckage of a streetcar in downtown Lisbon on Thursday, trying to determine why the popular tourist attraction derailed during the busy summer season, killing 16 people and injuring 21, five of them seriously.

Portugal’s attorney-general’s office said eight victims have been identified so far: five Portuguese, two South Koreans and a Swiss person.

There is “a high possibility,” based on recovered documents and other evidence, that the victims also include two Canadians, one American, one German and one Ukrainian, according to the head of the national investigative police, Luís Neves. Three remain to be identified.

In a statement on Thursday, Global Affairs Canada said it was aware of two Canadian citizens missing in Lisbon after the streetcar crash on Wednesday.