A woman in her 20s and a boy in his teens have also been taken to hospital following the incident.
Gardaí are appealing for witnesses following a serious road traffic collision that occurred in Limerick on Saturday 10 July.
Shortly after 11:30pm, Gardaí and emergency service attended the scene of a two car collision on the N21, Kilconlea in Abbeyfeale.
Two men, both in their early 20s, were taken to University Hospital Kerry where their condition has been described as critical. One of these men has since been moved to Cork University Hospital.
A woman in her 20s was also taken to University Hospital Kerry where her condition is described as stable.
A boy in his late teens, was taken to University Hospital Limerick where his condition is also understood to be stable.
The road is currently closed while Garda Forensic Collision Investigations take place. Local diversions are in place.
Gardaí are appealing to anyone who witnessed the incident to come forward. They are also appealing to anyone with video footage, including dash cam, from the location to make it available to them.
Anyone with information is asked to contact Newcastle West Garda station on 069 206 50, the Garda Confidential Line on 1800 666 111 or any Garda station.
