An unemployed bricklayer has shot two Italian policemen in a crowded square outside the premier's office just as the nation's new government was being sworn in.
The gunman's intended target was politicians, a top Italian official said after interviewing him.
Mired in recession and suffering from soaring unemployment, Italy has been in political paralysis since an inconclusive February election.
Sunday was supposed to be a hopeful day when debt-ridden Italy finally got a new government to solve its many problems. But shots rang out in Colonna Square in Rome near a busy shopping area shortly after 11.30am just as premier Enrico Letta and his new ministers were taking their oaths at the Quirinal presidential office about half a mile away.
The suspected gunman, dressed in a dark business suit, was immediately grabbed by other police outside Chigi Palace, which houses the premier's office and other government offices.
Rome prosecutor Pierfilippo Laviani told reporters he had questioned the alleged assailant, who was taken to a hospital with bruises after being wrestled to the ground.
He identified the man as Luigi Preiti, 49, from Calabria, a southern agricultural area plagued by organised crime and chronic unemployment.
Mr Laviani said Preiti had "confessed everything" and did not appear mentally unbalanced.
The prosecutor said: "He is a man full of problems, who lost his job, who lost everything. He was desperate. In general, he wanted to shoot at politicians, but given that he couldn't reach any, he shot at the Carabinieri (paramilitary police)."
One of the policemen, shot in the neck, was in critical condition. The other, shot in the leg, suffered a fracture, said doctors.