At least one person was killed and some 200 injured on Tuesday morning when two trains on Rome's underground system collided .
The incident took place shortly before 10.00 a.m. local time at the Piazza Vittorio underground station near Rome's main train station .
Firemen said a stationary train at the stop was hit from behind by another train on the same line .
The victim was a 30-year-old Italian woman. Initially, the driver of the moving train was also believed to have died but emergency services later denied this report. Around 60 of the injured were in a serious condition and at least four were said to be critical .
Most of the other injured were bruised and shocked .
Many of the passengers were treated on the spot as they emerged from the station exits while others were ferried to hospital in ambulances and buses .
According to some reports, a failure on the Metro network's central signalling system was to blame. The moving train was believed to have been given the green light to proceed from the station prior to Piazza Vittorio .
"At that point, the crash was inevitable and the impact very strong. The first carriage of the oncoming train ploughed right into the last carriage of the stationary train," Metro sources said .
Underground rail officials said both trains involved in the crash were brand new, high-tech models only recently introduced on the network .
The Spanish-made trains are to gradually replace the old trains running on the Metro system .
Rome Mayor Walter Veltroni, who was at the scene, said that "I've asked Metro managers to explain how something like this could have happened. The trains were both new and working" .
The scene at Piazza Vittorio was chaotic with rescue workers taking an hour to free some of the injured from the wreckage of the two trains .
Witnesses told reporters how they had initially feared a terrorist attack was to blame .
"Inside the carriage, people were crying out that a bomb had gone off. They were screaming 'It's a terrorist attack and we're all going to die'. We really were convinced it was a bomb," a university student told ANSA .
Another passenger who was inside the last carriage of the stationary train and was lucky to escape unscathed said: "I was leaning against the side of the carriage waiting for it to go when I saw another train approaching from behind. I thought it would stop but it just kept coming .
"Terrified, I moved to the front of the carriage and threw myself on the floor. Then I heard a huge crash. When I opened my eyes, all I could see was blood and injured people and all I could hear was a continual wailing. It was devastating" .
A journalist with state broadcaster RAI who was aboard one of the trains and also emerged unharmed said that "the impact was incredibly powerful despite the fact that the oncoming train had slowed down to enter the station" .
"The worst moment was when we got out of our carriage because the scene around us was one of total panic, with people crying and screaming," he said .
The accident caused widespread disruption in the capital, with the suspension of underground rail services and extensive traffic jams .
Italian President Giorgio Napolitano expressed his condolences for the victims of the crash .
Premier Romano Prodi was being informed of developments by Veltroni and Transport Minister Alessandro Bianchi .
The government will report to parliament on the incident on Tuesday afternoon .
