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Water from the Pawtuxet River encircles homes in West Warwick, R.I., on Wednesday. Rhode Island rivers overflowed their banks, causing flooding and road closures after three days of record-breaking rains. ((Charles Krupa/Associated Press))

Officials in a Rhode Island town have forced hundreds of people to leave the area, fearing a bridge upstream will collapse amid flooding.

The abutments on a bridge over the Pawtuxet River have washed out, Coventry Police Col. Ronald Da Silva said Wednesday.

A corner of a building near the bridge has already fallen in and authorities say there is a risk that more of it could collapse.

The bridge is about 60 metres long and two lanes wide.

Record-shattering rainstorms in Rhode Island have flooded the state, causing U.S. President Barack Obama on Wednesday morning to declare a state of emergency.

A storm Tuesday soaked all corners of Rhode Island, pushing rivers over their banks, closing roads and schools, and requiring hundreds of people to evacuate, including by boat. The rain finally tapered off by Tuesday afternoon, but resumed in the state capital, Providence, by evening.

Officials are bracing for what is expected to be the most severe flooding to hit the state in more than 100 years.

"None of us alive have seen the flooding that we are experiencing now or going to experience," Rhode Island Gov. Don Carcieri said Tuesday night. "This is unprecedented in our state's history."

First the economy, now flooding

Obama's declaration means the Federal Emergency Management Agency can step in to co-ordinate disaster relief efforts and provide emergency assistance.

The rain came as residents were still recovering from a storm two weeks ago that dumped as much as 25 centimetres of rain on the region.

Carcieri last week cited the state's "fragile economic climate" and an estimated $220-million-US state budget deficit when he asked Obama to declare a federal disaster. The state's unemployment rate has hovered for months around 13 per cent and has long been among the highest in the country.

Records fell across the northeastern U.S., including in Boston, New Jersey and parts of New York City.