The accident occurred on line 10, one of the latest, when a train crashed into another from behind. The company that operates the subway, Shanghai Shentong, had just announced that the line experienced delays due to equipment problems.
At least 270 people were injured, and some evacuated on stretchers. The accident blocked traffic in part of downtown to facilitate the movement of ambulances.
Shanghai, which has 23 million people, has expanded its network in recent years and some subway lines had problems, including faulty signaling and opening doors.