NSW Ambulance received a call at 9.52am on Monday with reports of injuries, a spokesman told AAP.
It's believed the train hit the buffer at the end of the line.
"The 10:11am train service from Richmond to Central has been cancelled," Sydney Trains tweeted on Monday.
Fire and Rescue NSW tweeted that three people were trapped and that there were a number of injuries with another six crews on en route.
Three people trapped after train derails at Richmond, Sydney Pics: Brett Saunders
