Emergency services have been called and a large part of the London North Circular Road (NW10) (Southbound) at the junction of Great Central Way has been cordoning off.
Police, firefighters from the LFB and Paramedics have all been scrambled to the incident that happened just before 1am on Friday morning.
It is understood that a man jumped off a bridge on the Great Central way bridge on to a live railway track near to the busy TFL train depot. It is unclear if the man was being chased prior to jumping or the circumstances.
The westbound carriageway remains blocked between Neasden Lane and Great Central Way a number of overnight bus services have been affected by the closure Routes 112, 232, 332.
Drivers are being asked to seek an alternative route. Traffic is flowing well on diversion.
The Met Police have been approached for comment