Rome wildfire may have been caused by arson.

The head of Rome's civil protection department has urged residents to donate blood after four emergency responders were seriously injured in a vast wildfire in the city's suburbs.

The four men - one firefighter and three civil protection volunteers - suffered severe burns while battling the blaze between the Torre Spaccata and Cinecittà districts on Wednesday.

Rome citizens are being urged to donate blood to the Sant'Eugenio hospital where the four emergency responders are in critical, life-threatening condition, doctors said on Thursday.

The firefighter suffered burns to 54 per cent of his body, while the three civil protection voluteers were also very seriously injured after becoming encircled by flames when the winds changed suddenly.

An investigation is underway into the cause of the fire, with arson not being ruled out.

In an interview with Corriere della Sera, Rome mayor Roberto Gualtieri said: "I ask citizens for help in reporting suspicious behaviour. Arsonists must be stopped by all means."