At least 34 people were killed and dozens more were hurt in the eastern Spanish city of Valencia Monday, after an underground train derailed and overturned. This is one of Spain's worst subway accidents in history.

Spanish television was filled with images of wounded passengers being rushed to hospitals Monday. The accident took place in Valencia early in the afternoon, Spanish time, and the subways were filled with commuters. According to local reports, an underground train ran off the tracks in a tunnel at high speed and overturned.

One local official told the Reuters news agency that it seemed the accident was caused by the train going excessively fast, and one of its wheels breaking off as it entered the tunnel.

One of the commuters on the train told Spanish TV she had heard an explosion and saw smoke in the subway car she was on. Like many of those interviewed, she was distraught. According to local news reports, passengers trapped in the subway rang for emergency services for assistance.

Several serious accidents have occurred on Spanish rail systems in recent years. In November, another subway accident in Valencia injured 16 people. And 19 were killed in another train crash, in 2003.

But so far the worst tragedy on Spain's rail system took place in March, 2004, when 191 people were killed in terrorist attacks targeting commuter trains in Madrid.

Spain's King Juan Carlos has expressed his condolences to victims and their loved ones involved in this latest subway accident. Local media reported Prime Minister Jose Luis Rodriguez Zapatero may cut short an official visit to India. The Vatican also announced Pope Benedict XVI was praying for those involved in the crash.