A pair of 97-year-old twin sisters are thought to have frozen to death after they fell over in the driveway in freezing conditions.

Jean Young Haley is believed to have tripped over in icy weather just outside her home in Barrington, Rhode Island, along with her twin Martha Young Williams as they returned from an evening out.

The pair were only spotted the following morning by a neighbour after a night in which temperature dropped to -11 degrees.

Police said the "tragic" incident is thought to have been an accident.

The force said the twins had gone for an evening out with a younger sister, aged 89, who had already left for home when they got into trouble at around 8.30pm.

"Ms Williams may have fallen in the driveway walking to her car. Ms Haley may have tripped on a rug on the floor of the garage as she attempted to enter her house to call for assistance," they said in a statement.

It added that the cause of death is not yet known but "extreme cold temperatures that evening may have been a factor".

Their twins' family issued a statement Monday thanking people who have extended condolences and recalling the pair as an inspiration with a great passion for life.

George Mihailides, the owner of a restaurants the pair often visited, added the women were "extraordinary - a real class act".