The man stabbed to death is believed to be aged in his 70s. (9NEWS)

A man has been arrested over the stabbing death of another man, believed to be aged in his 70s, in broad daylight in Melbourne's inner-north this afternoon.
Police believe an altercation occurred between the two men on the corner of Murray Road and Gilbert Road in Preston at 4.45pm.
A passer-by witnessed the violent attack and stopped her car to try and resuscitate the man until paramedics arrived.
Ambulance officers tried to revive the man, but he died a short time later.
The 35-year-old Preston man accused of the stabbing was arrested at the scene and is assisting police with their enquiries.
Murray Road is closed while police investigate.