Eight people were injured after a car ploughed into pedestrians in the centre of the northern Italian city of Modena, police said.
Four people are in a serious condition, the city mayor Massimo Mezzetti told broadcaster RaiNews24.
He said a woman was pinned against a shop window and required the amputation of both legs.
Police said they arrested the driver, a man in his thirties, and there was no further danger.
The driver is an Italian national born in Bergamo and a resident of the Modena area, the mayor added.
Read more from Sky News:
Man dies after shark attack in Australia
Eight dead after freight train hits bus in Thailand
"It seems (the driver) deliberately drove onto the sidewalk, hitting several people and crashing into a shop window. He then got out of his car and brandished a knife," said Mr Mezzetti.
He tried to flee but was stopped by some of the citizens involved in the crash and then by police, and was taken to headquarters for questioning.
One man who attempted to stop the driver suffered minor injuries, the mayor added.
Authorities are working to determine whether the driver was under the influence of substances or acted deliberately, the mayor said.
Witnesses reported the man was holding a knife, but he did not manage to stab anyone, the mayor said.
Victims were taken to hospitals in Modena and Bologna, with some of the most critical cases taken by helicopter.
"I express my solidarity with those who were injured and their families," Prime Minister Giorgia Meloni said in a post on X.
"What happened in Modena is extremely serious," Ms Meloni added.
(c) Sky News 2026: Eight injured after car ploughs into pedestrians in Italy
WHO declares global public health emergency over Ebola outbreak in Democratic Republic of Congo and Uganda
Man dies after second fatal shark attack in Australia
'Everyone is doing it': The dark art of GPS jamming in the Iran war
Freight train hits bus in Thailand - at least eight dead
Maldives suspends search for four Italians in underwater cave after military diver dies
Trump says freeing activist Jimmy Lai jailed in China is 'tough'
CIA chief visits Cuba as US demands 'fundamental changes'
Protests break out in Havana during Cuba's worst blackouts in decades - as minister says 'we have no fuel'
