Man stabbed to death at Campsie in Sydney's south-west

A man has been arrested after he was found covered in blood at a train station in Sydney's south-west, near to where another man was stabbed to death.

Emergency services were called to Amy Street in Campsie, near the back of St John's Anglican Church, at 2.50pm with reports a man had been stabbed multiple times.

The victim, believed to be in his 40s, was found lying on the footpath with severe injuries. He died at the scene.

It's alleged the man was stabbed after an argument with another man.

Police believe the men knew each other, but were unable to say what the argument was about.

A 39-year-old man who was covered in "forensic material" was seen a short time later sitting on a platform at nearby Campsie train station.

He was arrested as commuters watched from an opposite platform. He was taken to Campsie police station where he is currently being questioned.

Superintendent Michael McLean from Campsie Police said the man was not found with a knife. He described the situation as "quite confronting".

"Police attended the scene very quickly, there was an immediate response from police from Campsie as well as police from adjoining areas," Mr McLean said.

"There was a male seen on Campsie railway station. Based on the description that was provided to us and some physical evidence upon him, we took a decision to arrest him and he was taken to Campsie Police Station.

"At this stage we believe there may have been some forensic material on him."

Mr McLean said officers established three separate crime scenes - one where the man died, another nearby where clothing was found, and a third at the train station.

"These people were known to each other, I do not believe it was a random-style attack," Mr McLean said.

"What we do know is an altercation did occur between the two males. A knife was produced and ultimately the deceased male was stabbed."

All scenes were being examined on Wednesday evening by forensic officers.

A witness who discovered the body told Seven News the man had been stabbed and sliced in the abdomen, where the knife remained.

Part of Campsie train station was closed as police arrested the 39-year-old and examined the crime scene.

Sydney Trains said T3 services from the city were not stopping at the station due to a police operation. 

Train passengers were advised to change at Belmore for Campsie. Buses in the area were also delayed.

Large numbers of police responded to the stabbing, closing the road as a crime scene was established.

Officers cordoned off the road and footpath with crime scene tape, as a gazebo and sheets were set up on the footpath to block the man's body from view.

Anyone with information is urged to contact police.