Chinese state media say two subway trains have collided in Shanghai, injuring a number of passengers.
The official Xinhua news agency said one train slammed into the back of another as a result of equipment failures. Photos of bleeding and apparently unconscious passengers were posted on Internet microblogging sites.
There were no immediate reports on deaths or the number of injuries. However, the accident had similarities to a train wreck in July that killed 40 people and shattered public confidence in the nation's high-speed rail system.
That accident, in the city of Wenzhou near Shanghai, also involved a rear-end collision and was blamed on equipment failures.
China has poured billions of dollars into its scandal-plagued bullet train network, prompting critics to complain that Beijing has sacrificed safety in its quest for rapid economic growth.
The July crash prompted an unusual outpouring of public anger on social media and even in the normally supportive state-controlled press.