Another major fire darkened the skies over several districts of Rome over the weekend.
A fire broke out in the eastern part of the Italian capital on Saturday, spreading to several car junkyards and part of a park.
A large column of black smoke could be seen across the city.
Firefighters said the fire was under control on Saturday morning.
Around 100 firefighters were deployed in 50 vehicles, including a special fire engine from Ciampino Airport.
Four buildings were evacuated as a precautionary measure, affecting around 130 families, according to the media.
People around the fire have been urged to keep doors and windows closed and to wear a mask against toxic smoke when outdoors.
This was the fourth major fire in Rome in the past four weeks.
"It is now clear that Rome is under attack from pyromaniacs," said Claudio Mancini, a confidant of Mayor Roberto Gualtieri.
Observers assume that fires are being deliberately set to harm the city administration and the new mayor.
"The investigation will show whether it is a matter of lone perpetrators or organized crime," added Mancini.