More staff had to be brought in to cover the latest 'spike' in patients attending Belfast's Royal Victoria Hospital Accident and Emergency department.
The action taken last night after the dramatic rise in casualties was in line with hospital guidelines, according to the hospital's medical director.
Dr Tony Stevens said that an "extremely busy" A&E department was stretched but not strained after more than 250 patients visited the department in a 24-hour period from midnight on Sunday.
A management team had to be brought in to support staff because of the increase in demand, although Dr Stevens said that this was normal protocol.
"At the minute we have identified beds in all of our hospitals to deal with the patients we are treating," he said.
At least 10 patients had to be transferred from the RVH to other hospitals while around 27 people were waiting on trolleys.
Last week it was announced that a total of 40 extra nurses were to be appointed to the A&E and acute medical unit following a review of staffing levels.