The worst thing, said an American tourist describing the scene, was seeing the bodies of the dead and the injured under the bus.
At that stage, before the first emergency services crews arrived seconds later, the five who perished in the worst accident in the history of Dublin Bus were probably already dead, crushed under the wheels of the double decker bus.
They and the injured were either waiting to step on to the No 66 bus or were passing the stop on Wellington Quay, on the south side of the River Liffey.
One of the dead, originally from the Ukraine but living in Lucan, was waiting on the pavement and was on the phone to his 11-year-old daughter when he was struck.
Another who died was Margaret Trainor, from Coolock in north Dublin. Her friend Ruth McKenna told RTÉ that the dead woman's daughter witnessed the tragedy.
"I lost a very close friend. Margaret was on her way out to see us yesterday. It's horrific. Her daughter witnessed it because she left her here at the bus stop. Her family will never be the same again," said Ms McKenna.
She described the Wellington Quay bus stop as unsafe: "It's horrific that it takes such a tragedy, where somebody like Mags has to be killed in such a manner leaving a devastated family behind her, for anybody to listen. It's alright for Bertie Ahern being here yesterday and be upset but it's too late."
Her comments were echoed by Leixlip town councillor Catherine Murphy, who said she raised safety concerns about the "unsatisfactory terminus" at Wellington Quay with Dublin Bus managers just two weeks ago.
The stop, for buses to Lucan, Leixlip and Maynooth, was originally sited on Middle Abbey Street but moved 18 months ago due to Luas works in that area.
Ms Murphy said: "It's confined to a much tighter space than in its previous location and people had concerns about personal safety. At peak times people had to push through, but I don't think you could have predicted what has happened, and the awfulness of it."
Dublin Bus has a different interpretation of what was said at the meeting between the Leixlip representatives and its managers. The issue of safety was not raised and the concern was over the longer distance people had to walk from the shopping areas of the city.
There have been no concerns raised about safety at the Wellington Quay stop or any other one in the city, said Dublin Bus transport manager Mick Matthews.
Yesterday, flowers marked the spot where the five died. Bono and The Edge, who are co-owners of the Clarence Hotel the accident happened just outside the building left a floral tribute with a message of sympathy for the bereaved.