A German grandmother and her five-month-old grandson are missing after a flash flood swept through the house they were staying in near Pisa, in Tuscany.

The German family of holidaymakers reportedly called emergency services on Monday evening as soon as the nearby River Sterza broke its banks and water started coming into the house from under the door.

Local media said that the language barrier and the rescuers’ difficulties in locating the family meant it took some time for firefighters to arrive.

In the meantime, the family tried to climb to the higher floors of the house.

However, as they were doing so the baby fell into the water, Francesco Auriemma, the mayor of the town of Montecatini Val di Cecina, told Italian media.

His grandmother was swept away as she tried to rescue him. Other members of the family – the baby’s grandfather and his parents – managed to save themselves and were later rescued on the rooftop.

More than 100 firefighters are now searching for the woman and the baby, but are having to contend with the aftermath of the flood.

Some roads have collapsed and entire areas are covered in mud.

Firefighter Nicola Cianelli told Italian outlet Corriere della Sera that the river swelled up “incredibly quickly” and that the the wave that swept through the German family’s home was 2.5m (8ft) high and “extremely violent”.

The surrounding area has been battered by heavy rains since Monday, with more bad weather expected until at least the end of Wednesday.

Local farmers reported destroyed crops and devastated vineyards.

Eugenio Giani, the regional president, said the area had seen more rainfall in the space of six hours than normally falls over the course of one rainy month. It was the most intense bad weather since records began, he added.

Last week, the region of Emilia Romagna to the east of Tuscany suffered serious floods. More than 1,000 people had to be evacuated from their homes and two people went missing in Bagnacavallo, near Ravenna.