A man's feet have been severed after becoming stuck under a train at Town Hall Station.
It's believed the 60-year-old Chinese man fell on to the tracks about 12.10pm.
Multiple police and ambulance crews were called to the scene on platform one.
Trains were stopped while paramedics treated the man who slipped onto the track just seconds before a train hurtled into the station, and desperately tried to crawl out in time.
Police said the man had suffered significant injuries to his feet.
He was taken to Royal North Shore Hospital in a serious but stable condition.
Sydney Trains told passengers to allow for extra travel time due to the incident.
"Due to a person injured by a train at Town Hall, some services may experience delays and have changes to stopping patterns," they said.
They said the person had been safely removed from the rail corridor and was being taken care of by an emergency crew.
"Flow-on delays will impact some services," they said.
"Sydney Trains would like to thank our staff, members of the public, and emergency services that worked quickly to come to the injured man's assistance."