HONG KONG - Radical Hong Kong protesters disrupted the morning commute on Tuesday for a second straight day, blocking subway lines and clashing with police in some areas.

Service on four major subway lines that bring commuters into Hong Kong Island from Kowloon and the New Territories had either been suspended or delayed, MTR Corp. said on its website.

Train passengers have been escorted onto the tracks after obstacles were found on the tracks near Sha Tin station on the East Rail Line, Cable TV reported, citing a passenger on the train.

Commuters, some carrying briefcases, had to walk on the rail track to get back to Sha Tin station after a train stopped in the middle of tracks because of obstacles on the tracks.

Radicals also hurled petrol bombs onto the rail track near Hung Hom.

Around 7 am, radicals threw bricks and other hard objects from heights onto the ground, set up barricades and obstructed road junctions in Kowloon Tong, compelling police to fire tear gas around 8 am. Public buses were forced to cease service in the middle of roads after being trashed and painted with graffiti on windshields.