Angry Hong Kong commuters argued with protesters who blocked the doors on trains Tuesday morning, preventing them from leaving stations.

Service was delayed and partially suspended on the Island and Kwun Tong lines, subway operator MTR said. It cited “a number of train door obstructions” as well as someone activating a safety device at a platform on the Kwun Tong line.

AP video showed heated exchanges at Tiu Keng Leng station, where a crowd of protesters and commuters filled the platform and a stopped train.

The disruption is part of a pro-democracy movement that has seen hundreds of thousands take to the streets this summer for marches and rallies. The protests have shaken the government in Hong Kong and raised concern in Beijing. The city is part of China but has a fair degree of autonomy in local affairs.

Posts on Twitter showed long lines of commuters waiting for free shuttle buses provided by MTR to other subway stops.

Protesters conducted a similar action to block trains last week.

(AP)