Armed police and sniffer dogs swooped onto the platform and were able to detain the man.
Trains going to London Waterloo has been disrupted this morning as a terrific passenger took to Twitter.
One passenger @SilviaPadra tweeted: "Train stuck in Feltham, passenger says he has a weapon and is threatening other passengers. We can not leave until you are arrives. It's been 30 minutes now. "
A few minutes later Charlene Ferndandes tweeted: "Police are here with guns and a sniffer dog. Stuck on train. Really hoping it's not a real threat. "
South Western Railway has been disgruntled commuters that there what "a disruptive passnager at Feltham".
Trains were disrupted and delayed with some stucco at a standstill for half an hour.
South Western Railway has reported that disruptions are expected to last until noon.
A spokesperson said in a statement: "Following a passenger incident on a train between Staines and Twickenham, all lines have now been reopened.
We may need to cancel your train or change your train stops to your journey. "
The British Transport Police and the Metropolitan Police arrived at the station and said they were searched and arrested.
A spokesman for the BTP said: "Officers were called to Feltham station at 8.35.
"Colleagues from the Metropolitan Police also attended, and the man was searched but no weapons were found.
"He has been arrested under Section 5 of the Public Order and taken into custody.
Anyone who witnesses the incident is BTP by texting 61016 or calling 0800 40 50 40 quoting reference 109 of 31/10/18. "
THIS IS A BREAKING STORY.