THESSALONIKI — Rescuers using cranes and heavy machinery on Thursday searched the wreckage of trains involved in a deadly collision that sent Greece into national mourning and prompted strikes and protests over rail safety. The death toll from Wednesday’s head-on crash involving a passenger train and freight carrier remained at 43 as crews continue to check the burned out and twisted rail car remains for more bodies. More than 50 people remained hospitalized, most in the central Greek city of Larissa, some in serious condition. Railway workers’ associations called strikes, halting national rail services and the subway in Athens, to protest working conditions and what they described as a lack of modernization of the Greek rail system.

Wednesday’s collision occurred near the small town of Tempe in northern Greece, when a freight train loaded with heavy construction equipment smashed into a passenger service on Greece’s busiest line between Athens and the country’s second largest city, Thessaloniki. More than 300 people were on board the train, many of them students returning from a holiday weekend and annual Carnival celebrations around Greece.

As Greece reeled from its deadliest ever train disaster, Pope Francis and European leaders sent messages of sympathy. Among them were the Turkish Foreign Minister Mevlut Cavusoglu, whose country is recovering from devastating earthquakes last month. Ukrainian President Volodymyr Zelenskyy sent a message in Greek, writing “The people of Ukraine share the pain of the families of the victims. We wish a speedy recovery to all the injured.”

A stationmaster arrested following the rail disaster is due to appear in court Thursday as a judicial inquiry tries to establish why the two trains traveling in opposite directions were on the same track.

Transport Minister Kostas Karamanlis resigned following the crash, his replacement tasked with setting up an independent inquiry looking into the causes of the accident.

“Responsibility will be assigned,” Prime Minister Kyriakos Mitsotakis said in a televised address late Wednesday after visiting the scene of the collision. “We will work so that the words ‘never again’ … will not remain an empty pledge. That I promise you.”