Police have warned young people about the dangers of starting street fires.
It comes as part of a clampdown on illegal bonfires in the build-up to Hallowe'en and Bonfire Night.
Along with firefighters and the city council, police are encouraging residents not to leave rubbish and bulky items out for would-be arsonists to burn.
On Thursday night, fire crews had to tackle blazes in Bloxham Green and Elgin Avenue, in New Parks, Leicester.
New Parks beat officer Pc John Maddocks said: "Young people who set fires are risking their safety and those who live close by.
"Illegal fires are often built using household rubbish, aerosol cans and household cleaning fluids. They are highly combustible and create unpredictable blazes and dangerous fires.
"Not only are those responsible stealing items from gardens, they have even used wooden fencing and bins to light fires."
On November 4 and 5 last year, fire crews attended 25 illegal bonfires on public land, including nine in Bloxham Green .
Pc Maddocks arrested a 16-year-old boy who was later convicted of arson.
"He has now got a criminal conviction," Pc Maddocks said. "I would urge people who see anyone attempting to set fire to piles of rubbish to contact the police immediately."
Each year, illegal fires cost councils tens of thousands of pounds.
City councillor Jon Feeley said: "We operate a free bulk collection service. I would urge people not to leave items lying about that can be used to make bonfires."
One resident, who overlooks the green, said: "It's the same every year. It's disgusting and dangerous. On Thursday night they were at it again and we had the fire brigade out.
"They take stuff out of people's gardens – fences, bins, anything they can set fire to.
"They are risking people's lives."
The council, the police and the fire service have launched a Safer Bonfire Night campaign, which includes handing out leaflets to households urging them to be careful about disposing rubbish and suggesting they attend official bonfires.
Paul Moreland, watch manager at Leicester's Western fire and rescue station, said: "On average, we attend more than 100 deliberately started fires in the weeks leading up to Bonfire Night every year. Help us by not giving rubbish to people collecting for bonfires."
For a bulk collection, call 0116 252 7002 or visit:
www.leicester.gov.uk/recycling
