Workers have restrained a man after a shooting at a workplace in Melbourne’s west on Wednesday morning.

Police say the injured man sustained a “non-life-threatening” wound after being shot in his upper body about 8.30am.

Workers at the Ravenhall construction site at Rebecca Drive restrained the alleged shooter, believed to be aged in his 80s, until police arrived.

Tweet from @MelissaBrownABC

Annette, whose son was working at the worksite next door, told 3AW other workers restrained the alleged shooter.

“A guy has pulled up in a truck and came out and shot him twice … in the arm,” she said.

“It’s a citizen arrest. They’ve got him down.”

The alleged gunman is in police custody.

The exact circumstances leading up to the shooting are yet to be determined. Police remained at the worksite on Wednesday afternoon.

The injured man was taken to the Royal Melbourne Hospital.

Tweet from @KateMcG6

-with agencies