Vertical reports that according to local media reports the aircraft was on fire as it crashed.
AW609 prototype crashes; both pilots killed | Vertical Magazine - The Pulse of the Helicopter Industry
Here is the Google translation of the La Stampa article referenced form the OP:
A roar followed by a crash to the ground in the fields between Santhià and Tronzano: many in this morning saw the explosion in flight of military tiltrotor experimental Agusta Westland, hybrid of airplane and helicopter started from the basis of Vergiate, in the province of Varese.
The fear that the aircraft could fall over the area of Santhià (the first houses from the crash site three hundred meters away) was great, but just the readiness of the two airmen on board has avoided the bloodbath them, Pietro Venanzi, 53 , pilot Agusta Westland and Herbert Moran, a former Navy pilot Oregon native American but lives in Varese, died on the spot but by their courage and with a final maneuver capable of bringing the media into a peripheral area, avoided a massacre.
Meanwhile, the prosecutor of Vercelli has opened an investigation for manslaughter and aviatorio disaster, as well as the ANSV, the national agency for flight safety, opened an investigation and sent an own investigative team.
Witnesses tell of seeing him lean before catching fire. It was not the first test carried out over the skies of Vercelli. "It was flying low over the houses and it was on fire - told a group of students -. The pilot did well to take him up on the corn fields. If he fell in the city, it would be a massacre. "
"We have just learned that one of our prototype test fell - said this morning the CEO of Finmeccanica, Mauro Moretti, during his speech at the conference organized at Expo -. This does not have to stop in research and innovation. "