There have been reports of an explosion on the London Underground and three subway lines have been closed temporarily.
Four stations, Warren Street, Shepherds Bush, Oval and Oxford Circus, have been evacuated. Smoke was reported coming from one station.
BBC radio said that several "dummy" bombs or detonators exploded but authorities have not confirmed that. Other reports say an explosion in a haversack being carried by a tube traveller in Warren Street led to the alert.
In the Hackney area, police and sniffer dogs are reported surrounding a bus which had a number of windows blown out by a small device. But, other reports say there is a suspect package on the bus.
There has been just one casualty so far reported arising from the reported incidents.