ROME, Italy (CNN) -- Officials monitoring the River Tiber in Rome fear it could break its banks as early as Friday evening after a spate of bad weather in Italy -- but do not expect major flooding.



A rescue boat patrols the swollen River Tiber in central Rome early Friday.



Guido Bertolaso, the head of the Italian Civil Protection Department said that there is a 20 to 30 percent chance the river could break its banks and cause disruption in some neighborhoods in northern Rome, but not in the historic city center.



Two people have died in weather-related incidents elsewhere in Italy.



"We see that the flow is increasing, but it is not reaching a level that could be dangerous for the capital city of Italy," said Bertolaso about the Tiber, deeming the situation "crucial but not serious."



Bertolaso, calling the situation "quite extraordinary," labeled the flood threat and storms as the "fifth most serious situation of the past 100 years."



"But I think it is under control and the secret is to have the technology and the kind of organization to monitor the situation and to intervene if an emergency arises," he said. Bertolaso noted that authorities have been keeping a minute-by-minute watch because of heavy storms over the past few days.



He said the water level would probably increase for a few more hours and eventually peak between 8 p.m. and midnight local time Friday (between 1800 and 2200 GMT).



"If there will be no more rain, the situation is expected to stabilize," he said.



Rome Mayor Gianni Alemanno said he did not expect a major flood and noted that only a few dwellings have been evacuated -- primarily those inhabited by immigrants and Roma, who have set up makeshift camps on the banks of the Tiber.



"I just recommend people to stay at home and not to rush to the river banks to watch the river swelling," Alemanno said.



Hundreds of volunteers and civil protection officials have been deployed around Rome to monitor the situation, the Civil Protection Department said.



Sandbags have been lined up to contain any possible river overflow, and the fire brigade is ready with amphibious vehicles.



Police have blocked access to some pedestrian bridges and river banks, while residents are being urged to use their vehicles only if necessary.



Firefighters Thursday had to rescue dozens of motorists stranded in their cars. Because of the intense rain, the streets of some northern Rome neighborhoods were already flooded by water and covered in thick brown mud.



One woman died near Rome early Thursday when her car was submerged by a wave of water and mud in an underpass. The body of a second victim was found in the southern region of Calabria after a bridge collapsed.
What percent chance could the Tiber overflow? What has a 20 - 30 percent chance of overflowing? What country had a wave of bad weather? Who died near Rome? Where did the bridge collapse? What would overflow its banks?
20 to 30 River Tiber Italy One woman Calabria the River Tiber
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