A wheelie-bin arsonist left mounds of melted plastic and a Dunedin suburb "saturated" with police patrols yesterday morning.
A Fire Communications spokesman said eight burning wheelie-bins kept crews from three Dunedin fire stations busy in the Mornington-City Rise area.
Senior Sergeant Kelvin Lloyd, of Dunedin, said police were keeping an "open mind" about the spate of arsons.
"We don't know if the offender was on foot or in a vehicle."
The arsonist had set the contents of the bins on fire and had not used an accelerant, Snr Sgt Lloyd said.
When police were contacted about the fires, the area was "saturated" with police patrol cars and many people were spoken to, he said.
Police would like to hear from anyone who could assist with inquiries.
A Dunedin Fire Station crew was called to three wheelie-bin fires in Carroll St, at 5.47am and to another, in Eglinton Rd, at 6.39am.
Two minutes later, a St Kilda crew was called to a fire in William St.
The Dunedin crew then attended wheelie-bin fires in Alva St (6.49am) and Haig St (6.52am). A Lookout Point crew attended a fire in Mailer St at 7.03am.
Dunedin City Council solid waste manager Ian Featherston said the council was "annoyed" that an arsonist had targeted Dunedin City Council wheelie-bins.