Firefighters attended a fire at College St School in Caversham early on Saturday, after three wheelie bins were dragged to a classroom door and rubbish set alight.
Detective Sergeant Brett Roberts said the fire was the second in College St in less than three weeks.
The police flier said the first fire was at a recently renovated vacant house at 35 College St at 6am on May 28. And like the College Street School fire, rubbish was piled up against the building and set alight.
"There have been a number of rubbish bags fires in the South Dunedin area recently," Det Sgt Roberts said.
"In particular, the police are interested in any suspicious activity in the area or similar events that have not been reported to the police."
The fliers were distributed because police had no leads on the culprit(s), he said.
"We've done this because of the sheer numbers of fires in recent weeks. We keep getting clobbered with small fires - they're more a nuisance than anything.
"Distributing fliers is an easy way to ask people, who have information, to call us. We do it when we don't have enough staff to do door-to-door knocks."
In the past 10 days, bags of rubbish have been set on fire outside a church on the corner of Melbourne and King Edward Sts, another in a rubbish bin at Queen's High School in Surrey St, and a rubbish bag was set alight at the rear of stores in George St.
Det Sgt Roberts was confident the fires were not the work of a serial offender.
"They could well be kids."
He said a 10-year-old and an 11-year-old boy were identified in connection with the church fire, but they were not believed to be responsible for the others.
Police were still searching for a 15-year-old boy and girl in connection with the fire at a bus shelter outside Queen's High School, he said.
East Otago fire risk management officer Barry Gibson said house and business owners had a responsibility to look after their refuse and make sure it could not be used by anyone with malicious intent.
"That means putting your rubbish in an enclosed area, putting locking devices on wheelie bins and skips, and making sure they are not left up against buildings.
"Only put your rubbish out on the morning it is due to be collected. Don't leave it out all night."
Mr Gibson said about eight similar fires had been reported in the past fortnight, and suspected others had not been reported. The fires had the potential to cause serious injury or even death, and a fire behind a George St business last week came closest to causing both.
"The building nearly caught fire. Once one building goes up, the others attached to it go as well. Very often, there are people living inside these buildings."
Not all the recent fires had been lit at night, he said.
"The one on George St happened at 3pm. So, it's important that people notify police of any suspicious activity. It may be the only way we catch them."
