A man's leg was cut off when an escalator collapsed at a shopping mall here, the media reported on Monday.Zhang, 35, was cleaning the escalator on Saturday at the Longemont shopping mall in Shanghai's Changning district, the People's Daily reported. The comb plate on the escalator suddenly collapsed and trapped his left shin. His mop was also dragged into the cracks."The escalator has been closed and the case is under investigation," Shanghai authorities said on Sunday.This is the fourth accident involving escalators in China in recent days.