Last night ABC News in America screened images of the damage left by the London bombs on July 7, and of unexploded devices found in a car parked at Luton railway station.

This is a transcript of the interview between ABC presenters Elizabeth Vargas and Pierre Thomas, and Robert Ayers, a security analyst who was shown the pictures

VARGAS: We have exclusive, new details tonight about the terrorist attacks that killed 56 people in London two and a half weeks ago. There were four suicide bombings, three in the subway and one on a bus. ABC News has learned that the bombers left behind a large stash of unexploded bombs in a car, 16 in all. ABC News has also obtained the first photographs of the wreckage those bombs caused deep in the subway tunnels. In London, here is ABC's Pierre Thomas.

THOMAS: These exclusive photographs show the devastation inside the London subway lines after the July 7 attacks. This is the train at Edgware Road where seven people were killed. Eight people died on this train between the Liverpool and Aldgate stations. And this shows the train between King's Cross and Russell Square, where 27 were killed.

AYERS: There is considerable damage there. You can see it has blown out the sides, it has blown out the roof.

THOMAS: Bob Ayers is a security consultant with expertise in explosives, based here in London.

AYERS: That was a good-sized bomb that that man took down there and set off.

THOMAS: And there is more troubling news. ABC News has learned the July 7 plot may have been much larger than previously known. Sources familiar with the investigation tell us an additional 16 bombs were found in a car, believed rented by suicide bombers Shehzad Tanweer. That car was found five days after the attacks in Luton, when the bombers boarded a train to London.

AYERS: I believe that the explosives that were left in that car were left there for a second strike. But the Metropolitan Police responded so quickly, they were able to get to the car and take control of the car before the second team could get the explosives and leave.

THOMAS: These pictures obtained by ABC News show the bombs for the first time. The bombs were made of homemade high-explosives. Some were packaged like pancakes. Some had nails for use as shrapnel. An x- ray picture of one of the bombs in the trunk of the car show a deadly concoction.

AYERS: You see what is bulging on the sides of the bottle are nails. Many, many nails. And the nails are put there so that when the bomb goes off, the nails will tear tissue and kill people in the area. Bombs don't kill by concussion. Small bombs, they kill by the blast effects of fragments of glass or metal, and this is designed to kill people.

THOMAS: So now, Elizabeth, you understand why police here in London are so deeply concerned. They are in a race against time, against people who want to kill.

VARGAS: All right

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