A bus loaded with tourists from Turkey ran off a road in the Italian capital and dropped about 20 metres (65 feet) into a ravine late on Monday, killing 12 people, police said.
The bus, carrying about 30 people, was returning the tourists to their hotel after dinner when it crashed shortly after 11 pm (1000GMT), police said.
Police said six people were injured critically, including the Italian bus driver. Authorities said it was still unclear what caused the accident.
The bus reportedly was one of eight carrying a total of about 350 people -- all of them Ford auto dealers from Turkey, according to the ANSA and Apcom agencies.
A dispatcher at the Rome police headquarters, who said he was not authorised to release his name, said the bus fell about 20 metres (65 feet) into the yard of a private home in northwestern Rome.
He said rescue workers had to free some of the tourists who were trapped in the mangled metal, and transported them to area hospitals.
The bodies of the six women and six men killed in the accident were lined up on the grass and covered with white sheets.
{{/usCountry}}The bodies of the six women and six men killed in the accident were lined up on the grass and covered with white sheets.
{{/usCountry}}A Rome prosecutor later allowed their removal, saying they all had been identified by their relatives, who were traveling on the other buses, ANSA and Apcom said.
Mayor Walter Veltroni, who rushed to the scene of the accident, said Italy would do everything it could to assist Turkey in the tragedy.
"We are willing to do whatever the Turkish ambassador needs in this moment. They can count on us," Veltroni said.
"We will follow together what happens over the next few hours. Everything they need as far as repatriating the bodies, and any help needed for those here that are wounded, everything that we can do as a country we can do."
Italy's last fatal bus accident involving tourists happened in June 2003, when a double-decker bus headed from Germany to Italian beach vacations veered out of control and crashed outside the northern city of Vicenza. Six people died -- including two children -- and 38 were injured. Most of the bus's passengers were Moldovans who lived in Germany.