Three teenage boys and an 18-year-old man have been arrested after a fatal fight at Mernda Railway Station, in Melbourne’s outer north, on Friday evening.

Police were told a group of people were fighting on Bridge Inn Road about 5:50pm.

They arrived to find a 22-year-old local man with life-threatening injuries.

He was treated by paramedics but died at the scene.

A group of police officers sit at table under a large awning near a car that says SES and a shop that says Woolworths.

Mernda Railway Station and a number of shops were cordoned off while police investigated. (ABC News)

Footage from the scene shows a large section of the Mernda Railway Station and adjoining shops cordoned off as detectives and forensic officers investigated.

Homicide squad detectives arrested a 16-year-old boy, two 17-year-old boys and an 18-year-old man.

A dark cap lies between two yellow triangles on a concrete roadway near a pedestrian crossing, police car and police tape.

Investigations are continuing into the fatal fight at Mernda Railway Station. (ABC News)

They all remained in custody on Saturday morning as police continued to investigate the circumstances surrounding the man’s death.

Police are appealing for any witnesses, anyone who has footage of the incident or any other information to contact Crime Stoppers on 1800 333 000 or www.crimestoppersvic.com.au.

Two people in orange overalls bend over something on the ground as two people in dark clothing look in a bin behind police tape.

Police are appealing for information as investigations continue. (ABC News)