Five people, including a seven-year-old-boy, have been killed in two separate crashes in Co Cork and Co Mayo.
A man and a woman in their 60s, both US tourists travelling with their partners, were killed in a collision involving two cars and a lorry on the N20 Cork to Mallow road in north Cork.
The driver of their vehicle and the third passenger, a male and female also in their 60s, were injured and taken to Cork University Hospital with injuries described as non-life-threatening.
The driver of the second car involved was also taken to Cork University Hospital with injuries described as non-life-threatening while the driver of the truck was uninjured.
RTÉ are reporting a pregnant woman who was not involved in the crash but was at the Waterloo junction was also taken to hospital.
Diversions are in place on the N20 Cork to Mallow Road and gardaí are asking people travelling from Mallow to take alternative routes.
Gardaí have appealed for witnesses to contact Gurranabraher garda station on 021 4946200, The Garda Confidential Telephone Line 1800 666 111 or any garda station.
In Mayo, three people, including one child, have died in a collision involving a car and a truck on the N17 Galway to Sligo Road.
Two women in their 70s and 40s and a seven-year-old boy were killed in the collision at Lisduff just after midday, while the truck driver was uninjured.
They were pronounced dead at the scene where forensic investigators are now investigating.
Gardaí are appealing for witnesses and southbound traffic is being diverted to Ballyhaunis as motorists have been asked to avoid the Claremorris-Ballinrobe Junction.
Update 4.42pm: Spokesman for the Road Safety Authority Brian Farrell said it has "been an appalling day for road safety".
"To date this year 109 people have lost their lives on the roads," he said.
"If anything is to come from such loss of life maybe it reminds us of the fact that using the roads is the most dangerous thing we do every day. We really do have to be aware of the dangers and the risks every time we set foot or wheel on the road," Mr Farrell added.