The deaths of five members of the same Derry family in Buncrana on Sunday night is the sort of shocking, unthinkable tragedy that shakes people to the core.
It is hard to believe that a family day out to a seaside town on a sunny Palm Sunday could end in such a horrific way, with a car sinking into the sea so close to the shoreline and local people desperately willing the passengers to survive.
Sadly, it was not to be and the thoughts and prayers of people throughout Ireland will be with those who lost their lives, Sean McGrotty, his young sons Mark and Evan, his mother-in-law Ruth Daniels and her teenage daughter Jodie Lee.
The only consolation in this dreadful accident is that Mr McGrotty's four-month-old daughter Rionaghac-Ann survived, thanks to the outstanding bravery of Kerrykeel man Davitt Walsh, who swam out to the car and rescued the infant.
Mr Walsh is someone who put his own life at risk to help others and can justifiably be described as a hero. Tribute should also be paid to the lifeboat crews and emergency services who tried so hard to save this family in circumstances which were especially harrowing.
So many people have been affected by this terrible incident but foremost in all our thoughts will be Louise McGrotty, who has lost her husband, sons, mother and sister.
She will need every possible support as she deals with devastating loss on a scale that is hard for any of us to contemplate.
The town of Buncrana will also be trying to come to terms with the awful events of Sunday night.
This small seaside town has seen more than its share of tragedy in recent times, including the deaths of eight men in a horrific road crash in July 2010 and the murder of three local children in the Omagh bomb in 1998.
This latest loss of life will focus attention on safety in the vicinity of the pier, with suggestions that the car Mr McGrotty was driving slid on algae which had built up on the surface of the ferry slipway.
The authorities will need to look at all aspects of this tragedy to determine if anything could have been done to prevent loss of life and whether any measures need to be put in place to avert a similar catastrophe in the future.
It is a safety issue not confined to Buncrana but would have implications for any coastal spot where people regularly drive along piers and slipways.
For now, though, the main focus will be on supporting the heartbroken relatives of those who died on Sunday night who are now preparing for the funerals of five family members.
