Thirteen people have been killed and 10 injured in a bus accident in New York City, officials say.

The bus overturned on the New England Thruway in the Bronx at about 0530 (1030 GMT) on Saturday, a spokesman for the city's fire department said.

It slid on its side and then hit a light pole which sheared off the top of the bus, the spokesman said.

Six of the injured are said to be in a critical condition. The bus was carrying up to 33 passengers.

The light pole "went through the whole bus form front to rear", a fire department spokesman told the New York Times newspaper.