Line 4 of the Beijing subway has resumed operations after a malfunction that lasted about two hours on Friday morning, which caused large crowds at some stations.

The malfunction occurred around 7 am between the Zhongguancun station and Yuanmingyuan Park station of Beijing subway Line 4, after a signal system failure, according to Xinhua News Agency.

Normal operations resumed at 8:53 am after subway and police staff took measures to ease the traffic of passengers.

The malfunction resulted in passenger traffic congestion at some stations of Line 4 during the morning rush hour.