Police have detained two men on suspicion of murder and a woman was detained on suspicion of assisting an offender and remains in custody.
According to a police statement, events unfolded at 5.10pm yesterday (September 19) when emergency services were called to a report of a man who had been stabbed at a property in Park Way.
The air ambulance then landed in Horsham Park.
Two men aged 18 and 22, both from London, and a woman, aged 22, were arrested 40 minutes later at Littlehaven Railway Station.
Rail commuters had to make other arrangements as the line was closed for a period.