U.K. police called on Londoners to submit mobile phone images and other photographs to help them investigate a second, apparently less serious wave of explosions that shook the capital city on Thursday.
Police confirmed that there were four small explosions or attempted explosions in London Thursday afternoon, at or near the Oval, Warren Street and Shepherds Bush Underground train stations, and on a bus in Hackney in east London.
"At the moment the casualty numbers appear to be very low in the explosions and the bombs appear to be smaller than on the last occasion, but we don't know the implications of all this yet," Metropolitan Police Chief Sir Ian Blair told reporters, according to a transcript. "Clearly this is a very serious incident," he said.
A spokesman for the British Transport Police said one person was injured at Warren Street station, The Daily Mail newspaper reported.
Several Underground stations were evacuated and the London transport system was closed down for a short while as police tried to figure out what had taken place, Blair said. The British Broadcasting Corp. reported that the explosions involved only detonators, not actual explosives. It was unclear at the time of this report who may be responsible.
An initial examination revealed no sign of chemical agents at any of the four sites, police said.
Police immediately issued an appeal for mobile phone images or other photographs that may have been taken near the incidents in order to help with their investigations. The U.K. Police Service Web site has an area where users can upload photographs and also includes a telephone number where images can be sent via text message.
Police also called for mobile phone images following the terrorist bombings that struck London two weeks ago and killed 56 people, including the four bombers. The incidents have highlighted how the ubiquity of camera phones and digital cameras can contribute to the investigation of such incidents. Police also studied closed-circuit television footage and released an image of the four bombers captured shortly before the July 7 attacks.