A subway train derailed and overturned in the eastern Spanish city of Valencia on Monday, killing at least 30 people and injuring about a dozen, officials said. A preliminary investigation indicated that it was an accident, said Vicente Rambla, spokesman for the Valencia regional government. One train carriage derailed when it was leaving Jesus station in downtown Valencia, according to a spokeswoman for Valencia's emergency services department. Some 150 people were evacuated from the station. Spanish National Radio reported that there were no more people trapped inside the subway. The most likely cause of the accident is a tunnel wall collapsing onto the carriage, investigators said. Police cordoned off the area and an emergency mobile hospital was set up at the scene. TV footage on private TV station CNN+ showed emergency workers carrying injured people on stretchers as bystanders looked on. The accident comes as hundreds of thousands of people began traveling to Valencia for this week's World Meeting of the Families which will be attended Saturday and Sunday by Pope Benedict XVI. Other recent train accidents in Spain include one in Madrid in January 2005 when some 20 people were slightly injured when a train carrying passengers bumped into an empty train at Madrid's Atocha station. A more serious one occurred in June 2003 when 19 people were killed and 48 injured in a head-on crash in central Spain. The crash, in which a passenger train collided with a freight train, occurred outside the station in the town of Chinchilla. More than 60 million people used Valencia's subway system in 2005, according to the network's Web site, which averages out to some 165,000 people a day. Valencia is one of Spain's biggest cities with a population of 600,000. It is on the country's east coast some 300 kilometers (185 miles) from Madrid.