A firebug went on an arson spree around Melbourne's north on Wednesday night, lighting five separate grass and scrub fires.

The fires were lit within an hour and within one kilometre of each other around Dallas, Westmeadows and Broadmeadows.

The Crib Point fire was the work of a suspected arsonist. Credit:Keith Pakenham

Firefighters were called to the first fire at 9.39pm on Dallas Drive in Dallas. No sooner had they arrived they received another call for a fire on Raleigh Street, Westmeadows.

At 10.04pm a fire started on Hepburn Street, Dallas.