A man has been arrested after a stabbing in Melbourne's CBD.

Victoria Police said a man armed with a knife was behaving erratically and running through a shopping centre car park in Lonsdale about 6am on Thursday.

Two bystanders gave chase along Elizabeth Street and detained the man near the intersection with Lonsdale Street.

Police then arrived and arrested a 32-year-old Dallas man at the scene.

A 41-year-old Maddingley man who was involved in the arrest received a stab wound to the lower body and was taken to hospital, but the injury was not life-threatening.

A 35-year-old Sanctuary Lakes man also involved in the arrest was not hurt.

Victoria Police said the Public Order Response Team had increased patrols in the CBD following the random stabbing of a woman last month.

Anyone who

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