Italian firefighters have said that as well as 12 dead, scores of people have been injured in the train crash in the south of the country.
Emergency services are currently at the scene.
Italy's prime minister says the train crash that left at least a dozen dead "is a moment of tears".
Matteo Renzi pledged not to rest until the cause of the crash is determined.
Renzi was speaking in Milan after the head-on collision in the southern region of Puglia on Tuesday morning.
Emergency services are battling to rescue wounded passengers stuck in the wreckage of the crashed train.
At least a dozen passengers have been killed in the crash, which happened in the middle of the countryside, north of the city of Bari in the heel of Italy.
Footage from the scene shows ambulance crews helping the wounded and the wreckage of the train.
The carriages appear to have crumpled on impact in the head on collision and metal debris surrounds the tracks.
This is the first picture of the devastating wreckage of the train crash that left at least a dozen dead in Italy.
The picture shows the front carriages mangled with debris strewn in the olive grove beside the tracks.
The fire brigade fear more passengers may be dead as they continue the rescue operation.
At least a dozen passengers are dead after two trains crashed head on in Italy.
Firefighters fear there may be more victims, the local newspaper reported.
The president of the Regional Council of Puglia, Mario Loizou, said: "The news has deeply shaken me".
Two trains have crashed head on leaving at least 10 dead in Italy, the fire brigade said.
Dozens were also injured in the crash, which happened on a single stretch of track between the towns of Corato and Andria, police said.
An aerial image reportedly showed train carriages were smashed and crumpled by the head-on collision, with debris spread out on either side of the track.
The local newspaper reported that among those rescued was a small child who was taken to hospital in a helicopter.
No immediate reason was given for the crash, which happened in the middle of the countryside, north of the city of Bari in the heel of Italy.
Italian Prime Minister Matteo Renzi has condemned the attack on a Dhaka cafe as he confirmed that Italians had been killed.
Renzi said he would not disclose any more details until families of the dead are notified.
Reigning European champions Spain are out of Euro 2016 after a 2-0 defeat by Italy in Paris.
Goals from Giorgio Chiellini and Graziano Pelle, one in each half, saw off the lacklustre Spanish in their Round of 16 tie at the Stade de France.
Check out ITV's Euro 2016 website for a full report and highlights
Voting to leave the EU would exchange“autonomy for isolation, pride for weakness and identity for self-harm”, the Italian prime minister has warned.
Matteo Renzi said the UK is not a country that walks alone and leaving the union could make "Britain less great".
He wrote in the Guardian: "There is no super state in Brussels, no pedantic grocer who measures cucumbers and lives on arcane and exacting acronyms that obscure reality. Can London really fear this caricature of Brussels?”
He added: “[It] would not be a disaster, a tragedy or the end of the world for you in the UK chose to leave the EU. It would be worse, because it would be the wrong choice."
Prime Minister Matteo Renzi said Il Giornale's decision to give away free copies of the Nazi leader's political treatise was "squalid".Read the full story ›