A head-on collision of two trains left at least 20 dead and dozens injured near the town of Andria in southern Italy. Both trains were running on a single track when the accident took place. The toll is expected to rise further, BBC reported.

The cause of the mishap remains unclear, however, human error is suspected to be the likely reason. Some coaches of the four-carriage passenger trains were severely damaged, with nothing but debris remaining of a few. Local police chief Riccardo Zingaro said, “Some of the cars are completely crumpled, and rescuers are extracting people from the metal, many of them injured,” according to Sky News.

Local reports said one of the trains was travelling from Adria and the other from the nearby town of Corato. The mayor of Corato said the site of the accident resembled a plane crash.

Italian Prime Minister Matteo Renzi cancelled his trip to Milan and returned to Rome, following news of the collision. He called the accident a “moment of tears”, adding that they “won’t stop until we get a clear explanation over what happened”.