“An incoming train crashed into one that was stopped at the station,” fire department official Kim Kyung-su told a news conference.
About 1,000 people were evacuated, Kim said.
Seoul Metro official Chung Soo-young said the accident was caused by a signal failure and that two subway cars were derailed.
http://www.reuters.com/article/2014/05/02/us-southkorea-crash-idUSBREA4105S20140502