A harrowing 999 call from the July bombings has been heard in public for the first time as the authorities assess their response to the attacks.
Representatives of London's emergency and transport services have met to share views on the lessons learnt.
The London Assembly 7 July Review Committee was considering how best to prepare people for similar disasters.
One caller said of the Tavistock Square bus bombing: "There's people lying on the ground... there's people dead."
London Underground managing director Tim O'Toole told the committee that bearing in mind the chaos and difficulty of managing the emergency, the speed of communication had been "amazing".
But he said the Tube network used an "antiquated" and unreliable radio network underground, which was badly disrupted by the blast.
Instead of being able to use communication from the subterranean radio system on the Tube trains, managers in the network control centre were sometimes reliant on station staff running to and from the scene, Mr O'Toole said.
There is a private finance initiative scheme to update the network which should have been installed two years ago, and will not be completed until 2006, Mr O'Toole said.
"We absolutely need to get a more resilient radio system down in the tunnels.
"Communication in tunnels is still problematic."
Mr O'Toole said the explosions on Tube trains after 0851 BST had initially been thought to have been power surges, with the loud bangs initially being thought to be circuit boards blowing.
By 0920 BST the Tube's network control centre had changed the status of the incident to a "network emergency" from power surges.
Representatives of the Metropolitan Police told the committee Scotland Yard had been aware of the possibility of explosions by 0910 BST, and by 0912 BST this started to be disseminated to emergency services staff.
At 0925 BST a statement was put out that a major incident was going on.
But a public statement saying there were reports of multiple explosions on the Tube network was not released until 1020 BST, half an hour after the Tavistock Square bus bombing.
Scotland Yard Assistant Commissioner Alan Brown said officers were still struggling to confirm what was behind the explosions and "it was more important that there was accuracy rather than information that might have misled".
Mr Brown told the committee the attacks were "unprecedented".
"The loss of life was unlike any previous terrorist attack we had experienced," he said.
"The hours were filled with uncertainty, fear, pain and significant trauma for all involved in the tunnels and on the bus."
Most of those who addressed the committee said it was important that lessons were learned.
The Met apologised for using a national rate 0870 number for the casualty bureau hotline, which raised £30,000 profit for telecoms firms, since donated to charity. The choice was "inappropriate", and would not be repeated.
The London Fire Brigade was questioned over the moving of chief commanders to Hendon on the outskirts of London, and admitted it had been a mistake as it distanced them from their command centres.
The brigade also decided it needed another six crews to tackle emergencies.
The committee will publish its report next spring.
The London Assembly has also expressed an interest in hearing from Londoners or visitors of their experiences on 7 July.
Anyone wishing to recount their experiences of the day can send an email to: firstname.lastname@example.org.