FLORENCE, Italy (AFP) - Part of the embankment of the Arno river in Florence collapsed on Wednesday, plunging parked cars into a crater and sparking an evacuation of buildings next to the city's world-famous Ponte Vecchio bridge.
The stretch of road between the 14th century Ponte Vecchio and the Ponte alle Grazie caved in when a mains pipe it was sitting on burst in the early hours of the morning, dropping around 15 cars into a depression which filled with water.
"Seeing that chasm 200m from the Ponte Vecchio was a blow. When I got there this morning my heart ached," Florence Mayor Dario Nardella told Italian media, as residents and tourists hovered at the scene, snapping photographs.
"But I assure you there is no danger to the people of Florence and the historic city centre is completely safe," he said.
The collapse affected about 200m of the embankment and authorities stopped traffic along the road.
Nardella said he hoped the residents evacuated from two buildings near the chasm would be able to return home later on Wednesday.
Local geologist Vittorio Doriano told Il Tempo daily that the collapse was caused by two blowouts in the water pipe, one around 1am and the other a few hours later which caused "considerable damage".
"It shows the leak had been there some time," Doriano said, adding that the repairs would be "a lengthy job".
Italy's Transport Minister Riccardo Nencini said the government was following the "complex situation" closely and Nardella said local magistrates had opened a preliminary probe which would look at whether water company Publiacqua was to blame.
Residents alerted emergency services after cracks appeared in the road following the first break in the pipe, and 12 cars were moved.
Critics said Publiacqua should then have turned off the water supply to the area in a bid to prevent further damage.
As firemen stood guard around the sunken road just metres from the Ponte Vecchio - where thousands of tourists snap selfies daily among chocolate-box jewellery stores - Florentines and opposition politicians took to social networks in anger.
The collapse "raises the curtain on the criminal management of water resources in Florence", said Federica Daga, a member of the anti-establishment Five Star movement, blaming not just the mayor but his predecessor, current Prime Minister Matteo Renzi.
"Publiacqua has always justified the exorbitant costs of its water bills - 402 euros per family in 2015 - with the enormous amount of investments in the network. The truth will out in the end. The damage to Florence is incalculable," she said.
Parts of the city were without water on Wednesday, as were parts of nearby Prato, according to media reports.