Two passengers have been stabbed to death after they complained about a man humming on a train, say reports in China.
The knifeman was humming along to his CD player when three people in the carriage complained about the noise.
A fight began and the trio wrestled the man to the floor and began beating him, said the state-run Xinhua news agency.
The man — identified only by his surname Yan — then pulled out a blade and stabbed all three of them.
One died on the train, while another died later in hospital.
The third man was taken to hospital and is recovering from his injuries.
Yan was arrested by police on the train, which was travelling from Kunming to Chengdu.