Three motorcyclists were killed and a pillion passenger seriously injured in separate accidents in the space of just eight hours.
One crash happened in Dublin, while in Limerick two men died within 10 minutes of each other in separate accidents. All the crashes were single-vehicle incidents.
The deaths of the three men have been described as "absolutely shocking".
In the early hours of yesterday, a motorcyclist in Dublin was killed and the pillion passenger was left seriously injured following a crash on the Old Cabra Road, Dublin 7. The rider of the motorcycle, Jesus Gomez (35), was pronounced dead at the scene.
He was killed close to his home on Navan Road in Dublin. The passenger, a man in his 40s, was taken to the Mater Hospital, gardai confirmed.
At around 7.30pm on Saturday in Limerick, a man in his 50s was seriously injured when his bike struck a roundabout at Quinn's Cross, Mungret.
He was treated at the scene by emergency services personnel and taken by ambulance to University Hospital Limerick where he was pronounced dead a short time later.
He was named locally as Andrew Szynka from Dooradoyle Road, Limerick.
Meanwhile, a man in his 20s was seriously injured after his bike left the road at O'Malley Park in Limerick at around 7.40pm.
He was rushed to University Hospital Limerick where he was pronounced dead a short time later.
He has been named locally as Thomas Whelan (25), from Limerick's South Circular Road. Mr Whelan was on bail, appealing an 11-month jail sentence for leaving the scene of a fatal road accident in which a passenger fell out of his car before being struck by an oncoming vehicle.
Responding to the incident at O'Malley Park, paramedics found Mr Whelan with critical injuries after his bike collided with an obstacle in the estate. He was thrown from the machine and suffered serious injuries. He died shortly after at University Hospital Limerick. A father-of-three, he had more than 180 previous convictions.
Limerick City Mayor Sean Lynch described the accidents as "terrible" and "absolutely shocking".
"I want to offer my deepest sympathies to the families and everyone involved.
"It's terrible, absolutely shocking. There are no words that can describe that loss and tragedy. As mayor of the city, my door is always open," Councillor Lynch said.
An Garda Siochana says there have been 16 road deaths in July, with 93 deaths in total so far this year.