One of the four victims was the Portuguese train driver and “there are dozens of other victims,” the local deputy Mayor said.
The train was carrying 63 passengers and the accident occurred near the Spanish station of O Porriño.
An Adif spokesman, speaking to Spanish newspaper El País, said that the reasons for the accident were unknown.
Spanish train company Refe Nacional Ferroviária de Espanha (Renfe) told Lusa News Agency that the train was owned by Portuguese railway company CP, had a Portuguese driver and 63 passengers on board.
The Vigo to Porto service has been jointly operated by Portuguese rail company CP and Spain’s Renfe since the “Celta” line was opened in 2011.
A source from CP confirmed that the driver was Portuguese and the crew were a mixture of both Portuguese and Spanish nationals.

The four people killed in Friday’s accident, were the Portuguese driver, a U.S. national, and two Spaniards (the ticket inspector and a trainee driver) who were buried on Sunday.
Rail accident investigator, Edmundo Parras, said on Tuesday that “everything points towards excess speed” as the cause of the crash at O Porriño, in Galicia.
The Portuguese train company CP and its Spanish counterpart Renfe acknowledged that there were works on the line where the crash happened and so the train should have been travelling much slower than it was. TPN/Lusa