National road policing manager Superintendent Steve Greally said it was an "incredibly sad and frustrating start to the long weekend".
"It's tragic for those families who are now dealing with the grief and aftermath of a road death," he said.
"Drivers need to take responsibility every time they get behind the wheel or on their bike.
"Make sure you drive to the weather conditions, if not for yourself, then do it for those who love you and want you to be safe, and for the others who share the road with you."
He said making smart decisions on the road is done by following the basic road safety rules.
"These include checking your speed, driving to the conditions, avoiding alcohol, taking rest breaks and always wearing your seatbelt," Mr Greally said.
"Most drivers do a great job, and we congratulate them for making sound decisions.
It's the mistakes and poor judgment of the risk takers who put the lives of the innocent in danger."