A day of terror on the London Underground. The bombs go off 12 years ago.

"There were people there we couldn't help. The dead were all around us."

- Former Paramedic Sandie Davis Roberts.

It is twelve years ago on Tuesday 7th July since suicide bombers set off explosions in the London underground and on a London bus, killing dozens and injuring hundreds.

A former English paramedic now living in Auckland spent hours helping the injured in one wrecked carriage. Sandie Davis Roberts recalls it was a scene of complete carnage.

8.49am, Thursday morning rush hour on the London Tube; Bombs exploded in three crowded trains, and an hour later a fourth went off in a bus carrying many who'd just been evacuated from the underground.

Fifty two people were killed and 700 hundred injured in Britain's first ever suicide attacks.

The bombings came one day after London had won its bid to host the 2012 Olympic Games with a campaign which had highlighted the city's multi-cultural population. Three of the bombers themselves were British born sons of Pakistani immigrants while the fourth was born in Jamaica.

Amongst the confusion and panic following the attack came dozens of professional emergency teams, among them Sandie Davis Roberts who was a senior paramedic of sixteen years' experience with the East Anglia Ambulance service. It was around noon on the 7th that Sandie in her ambulance was called into London.

"We thought we would take over the regular work of the London teams while they coped with the emergency", Sandie says.

But soon she was ordered to the Aldgate tube station, where she and her colleague had to traipse down immobilised escalators, along the rail tracks to the wrecked train.

"It was all very hazy and smoky, and really quiet, until we came across this scene of carnage". A bit like hell she imagines.

Sandie recalls the smell too; "burnt rubber, hot mechanical smells, and the noise! The sound of cutting machinery; there was surgeon next to me, amputating a leg."

The first person she helped was a woman trapped in a mangled door. She was covered in burns and cuts.

"She was angry", says Sandie "asking what sort of people would do this sort of thing"; only in stronger language. Her name was Felicity. Close by, a young man had a badly lacerated leg.

"He was praying."

Then she helped a surgeon who was trying to stitch together the badly damaged face of a well-dressed business woman. Sandie doubts she survived…

Go to this episode on rnz.co.nz for more details