Philadelphia rocked by explosions

At least two high-rise buildings in Philadelphia have been evacuated after a series of underground explosions.

The blasts were apparently caused by an underground power cable malfunction, local media reported. There were no reports of injuries.

TV pictures showed smoke pouring from a manhole cover and hundreds of office workers milling around in the street.

The blasts occurred near an underground rail station, but officials said services were running normally.

Workers for the Peco electricity company reported two or three explosions in the basement beneath a building in central Philadelphia, said Lisa Rotolo, a spokeswoman for the Philadelphia police.

There were also reports of a fire.

Several streets were closed off by police.