At least 41 people (including the driver) have been killed, and another 47 injured, in a Metro crash which occurred on Monday in the Spanish city of Valencia.  The accident occurred at around 1300 local time (1100GMT) - one of the busiest times of the day, when many commuters are heading home for their afternoon siesta.  An additional 150 people had to be evacuated from the tunnel because of the derailment.

Two carriages of the train derailed between the Plaza de Espana and Jesus stations, on the oldest line in the city's underground network.
Excluding the Madrid terrorist bombings of 2004 (which killed 191 people), this accident is the worst ever to occur on the entire Spanish mass transit network, and officials have announced two possible causes of the crash - either the driver exceeding the speed limit, or a possible defective wheel.  However, independent observers comment that the train involved in the accident passed a routine safety inspection only the week before, so an unsafe wheel is unlikely to be the cause.
The announced 3 days of morning will only be observed in and around Valencia, and not throughout Spain (unlike the mourning after the Madrid train bombings of 2004).