Five people were killed at the crash scene on Dublin’s Wellington Quay and 20 others were injured, some seriously.
The Dublin Fire Brigade had to use special lifting equipment to free people trapped under the bus.
The accident, the worst in the history if Dublin Bus, occurred during lunchtime on Saturday.
Wellington Quay is on the south side of the River Liffey and includes the Clarence Hotel, which is owned by rock band U2.
As of presstime, there was no clear indication as to how the out-of-service bus lost control and drove into pedestrians who were boarding another bus. The driver of the out-of-control bus reportedly has a 20-year exemplary record and had recently undergone an advance driving course in Britain.
Both buses were part of the fleet run by Dublin Bus, the major provider of bus transportation in the Irish capital.
The bus that was taking passengers on board was the number 66, which travels to the western suburbs of Dublin, including Lucan.
A Dublin Bus spokesman said Monday that the first stage of the inquiry would likely be completed within four weeks. The inquiry panel would include experts from Sweden, Germany and Britain.
The drivers of both buses are to interviewed by gardai after receiving counseling. Both are reported to be traumatized. They were released from hospital Monday.
There were no indication that the driver of the out-of-service bus had suffered a heart attack or any other medical trauma.
The stop where the fatal accident occurred had been the focus of safety concerns for some time. It was a temporary stop created 18 months ago as a result of nearby construction on the Luas light rail system.
Discussions over the safety of the stop took place as recently as two weeks ago between local city councilors and officials of the bus company. Questions had been raised about the severe crowding along the stretch of pavement where the temporary stop was located. And more question are to be raised in the D