The collision occurred on the M9 Northbound at Junction 3 at about 03:00 local time on Sunday
Post-mortem examinations are to be carried out later on the bodies of five teenage boys killed when their car being driven the wrong way down a motorway in County Kildare collided head-on with another car.
Three women, two aged in their 30s and one in her 20s, and a child who were in the second car were taken to hospital with serious injuries.
The crash happened between junction 3 and junction 4 of the M9 motorway, at Moone, at about 03:00 local time on Sunday.
The vehicle the teenage boys were in was travelling southbound on the northbound carriageway when it hit the second car.
Gardaí (Irish police) have said no pursuit was taking place before the collision occurred.
They have appealed for witnesses to the crash or anyone driving on that stretch of the motorway at the time to contact them.
Forensic investigators have completed their examination of the scene.
Garda Commissioner Justin Kelly described those injured in the crash as "family members" who were "travelling innocently" when they were struck by the car driving on the wrong side of the motorway.
Garda Commissioner Justin Kelly described the crash as a "horrific incident"
He described it as a "horrific incident" and "irresponsible and dangerous driving".
"What makes this reckless behaviour even more appalling is that in some cases it is being done for social media likes regardless of the potentially devastating impact it might have on innocent people and themselves."
Kelly added that police "do what they can to stop such vehicles while also taking into consideration all other road users".
"Gardaí are put in a really challenging situation dealing with such incidents."
Sinn Féin TD for Kildare South Shónagh Ní Raghallaigh described the scenes as "absolutely catastrophic".
