Chinese state television showed surveillance camera footage of the moment a janitor's foot was caught in an escalator at a shopping mall in Shanghai late Saturday night.

The footage, which was acquired from the mall by state broadcaster CCTV and released today, shows two people jumping over the top platform of the escalator just before a janitor, surnamed Zhang, walked over to mop its steps.

Within seconds of stepping over the escalator's top platform, Zhang slipped and his left foot was caught between a gap in the escalator's steps.

It took local firefighters around 20 minutes to free Zhang from the escalator's grasp, but doctors at a local hospital were unable to save his foot and were forced to amputate it, CCTV said.

Zhang is still recovering at the local hospital, CCTV added.

Authorities from the Market Monitoring Bureau of Shanghai's Changning district told CCTV that they are now conducting an investigation into the incident.

The escalator, which was manufactured in 2004, has been closed off from the public since Saturday's incident, CCTV said.