A chartered bus carrying visitors to a state prison slid off an icy road and down a steep embankment early Saturday, injuring 28 people, authorities said.

The accident occurred just after 9 a.m. on state Route 17 in Chemung, near the New York-Pennsylvania border, said trooper William Stavinski of the state police."Within the span of 10 minutes, the roads iced right up with a fine misty rain, then it turned to hail and a heavy snow," said a state trooper in Owego, who would not give his name.

The eastbound bus, carrying 49 passengers, originated in New York City and was bound for Elmira, said Frank Oliver, spokesman at Robert Packer Hospital in Sayre, Pa., where several of the victims were taken.

The bus, chartered from the Cambridge Bus Co. of New York, carried relatives going to visit inmates at a state prison at Elmira.

Oliver said 22 people were treated at the hospital. Three were in critical condition.