The severe floods in Venice that left most of the Italian city under water, are a direct result of climate change, the mayor says.
The highest water levels in the region for more than 50 years will leave a "permanent mark", said Venice Mayor Luigi Bruniaro.
"Now the government must hear," he added. "These are the effects of climate change … the costs will be high."
The waters of Venice reached a peak of 1.87 m (6 ft), according to the tide monitoring center. Only once after official records began in 1923 the tide was higher, reaching 1.94 m in 1966.
Images showed that popular tourist sites remained completely flooded and people were walking the streets while Venice was hit by a storm.
St. Mark's Square – one of the lowest parts of the city – was one of the hardest hit areas.
The Basilica of Saint Mark has been flooded for the sixth time in 1200 years, according to church records. Mr Bruniaro said the famous landmark had suffered "serious damage". The crypt is completely flooded and there are concerns of structural damage to the columns of the basilica.
Pierpaolo Campostrini, Member of the Council of the Saint Mark said four of those floods have occurred in the last 20 years.
The City of Venice is made up of more than 100 islands in the lagoon on the northeast coast of Italy .
Two people died on Pelestrina Island, a thin strip of land separating the lagoon from the Adriatic Sea. A man punched himself while trying to start a pump at his home, and another man was found dead elsewhere.
Mr Brugnaro said the damage was "enormous" and that he would announce the state of the disaster, warning that the project to assist the prevention of the devastating floods of the Venetian lagoon "must be completed soon".
"The situation is dramatic. We ask the government to help us," he said on Twitter, adding that schools would remain closed until the water level disappears.
He also urged local businesses to share photos and video footage of the devastation that he believed would be useful , when seeking financial assistance from the government.
People all over town were flooding through the floods.
A number of businesses are affected. Chairs and tables could be seen floating outside cafes and restaurants.
In the shops, workers try to move their water supplies to prevent further damage.
A shopkeeper who was not named was told by the Italian public operator Rai: "The city is on its knees."
Three water buses sank in Venice , but tourists continued to explore the sights as they could.
A French couple told AFP news agency that they had "effectively switched" after some of the timber platforms around the city in flood prone areas.
A number of boats were spotted Wednesday morning.
A project to protect the city from floods has been ongoing since 2003, but is affected by rising costs, scandals and delays.