The child's mum and dad and his grandfather were rescued from the roof of their holiday home in Pisa province, the fire service said.

More than 100 people - as well as divers, dogs, drones and a helicopter - are looking for the pair after the Sterza river broke its banks and floodwater rushed into the house.

The German family called for help around 9.30pm on Monday, but as they tried to climb higher the baby reportedly fell into the water - with his grandmother also lost as she tried to save him.

Firefighters posted a video on X of the search in Montecatini Val di Cecina, showing floodwater flowing through the gates of a property and rescuers with torches wading through.

Nicola Ciannelli, commander of the local fire service, told Corriere della Sera a "very violent" 2.5-metre flood wave had hit the house.

Other people in the area reportedly saved themselves by also climbing to higher floors of their homes or into trees.

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"We always aim at finding people alive, but this accident doesn't leave us many hopes. The situation is very, very critical," a spokesperson for the firefighters, Luca Cari, told SkyTG24.

Multiple regions of Italy have been under an alert for heavy rain, but the most serious has been in the Tuscany region - particularly Livorno and Pisa provinces.

The Emilia-Romagna region of northern Italy was also hit by floods last week, with more than 1,000 people forced to evacuate.