Hundreds of rail passengers were left stranded for hours in Spain after around 600 metres of fibre optic signalling cables were stolen.
The railway infrastructure company ADIF confirmed on Monday that the cables had been removed overnight in the region of Catalonia.
The theft forced Spain's state-owned railway operator Renfe to suspend the bullet train service between the country's two biggest cities; Madrid and Barcelona.
Passengers and holidaymakers crowded platforms before trains resumed service. An ADIF spokesperson told the Associated Press that at least 15 train departures were likely cancelled.
Catalonia regional police Mossos d’Esquadra said on Twitter that a 19-year-old man had been arrested on suspicion of theft near Santa Oliva.
Police have not ruled out making more arrests, they added.