A prisoner in Italy is thought to have used a drone to smuggle a gun into his jail before shooting fellow inmates, authorities said.
The 28-year-old man -- who has links to the Camorra mafia in Naples -- fired three shots at other prisoners through cell bars, a prison union has said.
There were no reports of any injuries, the union added.
The incident took place at the high-security Frosinone prison, around 100 kilometres southeast of the capital, Rome.
It is believed the prisoner had fired the handgun at inmates he had previously had an altercation with a few days earlier.
"He threatened a guard by asking him for the keys to the cell," said Donato Capece, secretary-general of the Sappe autonomous prison union.
"The cornered colleague had to give the keys but the inmate did not manage to open the door," he added.
The 28-year-old man had also smuggled a mobile phone into the prison to contact his lawyer, before turning himself in to the authorities.
He handed over the weapon and the phone, but not without removing the SIM card and swallowing it, Capece said.
"We assume that the weapon arrived by drone, but we have no confirmation of this," he added.
The incident was the latest in a series that have raised concerns over the poor management of Italy’s cramped prisons.
Italy has the highest prison overcrowding in the European Union, with 120 prisoners per 100 places, compared with 115 in France, and 70.8 in Spain, according to a 2020 Council of Europe report.
The Minister of Justice, Marta Cartabia, announced that the head of the Italian prison administration would travel to Frosinone on Monday.
In June, Italian media published images of prison guards beating inmates with truncheons and punches in April 2020, in response to protects during the COVID-19 pandemic.