British television is showing footage of a double-decker bus in London parked by the side of the road. The operator says its windows have been blown out.
The footage was aired on Sky T-V as police investigate the report of an incident on a bus in east London. In the footage, nobody was on board the bus or nearby -- and the streets appear to have been cordoned off.
Meanwhile, authorities have evacuated three London Underground stations following reports of smoke and explosions. Men dressed in chemical protection suits are preparing to enter one of the stations.
Police have cordoned off streets, and officers with sniffer dogs are checking the areas.