A high-speed passenger train derailed and slammed into an oncoming service in southern Spain on Sunday night, killing at least 39 people and injuring more than 120 in what officials described as an “extremely strange” disaster on one of Europe’s most modern rail networks.

The collision occurred near the town of Adamuz, in the province of Cordoba, when a Malaga-to-Madrid train operated by private company Iryo jumped the tracks at around 7:45 p.m. The rear section crossed onto the opposite line and struck a Madrid-to-Huelva train run by state operator Renfe, derailing both services, authorities said.

Spain’s Interior Ministry confirmed Monday that 39 deaths had been verified, sharply revising an earlier toll of 21. At least 123 people were injured, including five in critical condition and 24 seriously hurt. Officials warned the death toll could still rise.

Transport Minister Oscar Puente said the crash occurred on a straight, recently renovated stretch of track, a detail that has baffled investigators.

“This is a very strange accident,” Puente told reporters. “The train was practically new, the infrastructure was renewed just months ago, and there is nothing obvious at this stage to explain what happened.”