By Jo Twist
BBC News website technology reporter
Mobile phones provided some of the more immediate and vivid images of the bomb attacks in London.
Mobile video footage shot by commuters from inside London Underground carriages appeared quickly on global news networks and across the net.
As video mobiles grow more popular in Europe, they are letting people capture the first scenes of chaos before TV.
The attacks on the London Underground and a double-decker bus killed more than 50 and left 700 injured.
Flood of photos
Hundreds of mobile photos and several mobile videos have surfaced documenting the moments after the four blasts.
Blogs, photo sharing websites, online news sites, and TV news used their images in the minutes and hours immediately following the attacks.
Many people commenting on online photo sharing community site Flickr said it was their first port of call to get news and images.
Within minutes and hours, news of explosions filtered through other blog sites and many moblogs - blogs which use mobile phone photos - collected the images.
The BBC News and Sky News websites, among others, immediately responded and called for readers to send in their images, footage and accounts of the events.
Around 1,000 photos and 20 pieces of amateur video were sent in to the BBC News website, with many being featured on the site.
"Within minutes we were receiving people's written accounts and their still pictures," said BBC News Interactive editor Pete Clifton.
"An image of the bus with its roof torn away was sent to us by a reader inside an hour, and it was our main picture on the front page for a large part of the day.
"By the end of the day many of the images on the site had been provided by our users, and many of them were subsequently used by many other BBC services and national newspapers as well.
"It certainly showed the power of what our users can do when they are close to a terrible event like this," said Mr Clifton.
Although data transfer and calls cannot be made on a mobile in most of the London underground network, photo, video and other such functions do work.
The first images showed people making their way out of smoke and soot-filled carriages, while other footage showed the rescue efforts that took place above ground.
Third-generation (3G) and second-generation phones that can shoot video are becoming more popular in the UK, where mobile penetration is more than 80%.
The use of mobile reporting in mainstream news is a sign of the changing relationship between journalists and non-journalists, and is proving a powerful way to report events before TV cameras arrive.
It has been called "open source news" or citizen journalism and was well-used during last year's US election campaign.
News organisations in Japan were the first to recognise the power of mobiles, and often turn to such electronic newsgathering to get the first images.
In the aftermath of the Asian tsunami last December, mobile footage of the moments the waves crashed in were beamed all over the world.
In November last year, the dead body of Dutch film maker Theo van Gogh was snapped by a passer-by on a mobile before professional photographers reached the scene.
The picture appeared on the pages of Telegraaf, a daily Amsterdam newspaper, and made the news globally.
The BBC also tested mobile technology formally in a trial broadcast last year.
Tools of the trade
Unlike TV cameras, mobile phones only need a functioning network to send back moving images. This can be done at the touch of a couple of buttons.
TV crews often need feed links and complex set-ups to file back their high-quality images.
The grainy quality of the moving mobile images will improve over time, but news organisations say viewers forgive the quality as they understand the circumstances in which such footage is often shot.
Websites and moblogs have also started to appear with images of support for those affected by the blasts.
One such moblog, We Are Not Afraid, features dozens of images of people, many from the US, holding up messages reading "We are not afraid".
Such images have also been appearing Flickr, which quickly became an easily searchable depository for images of the events.
Mobiles are also proving crucial investigative tools too. Authorities will be scouring mobile records in the bid to find who was responsible for the attacks.