The Garda Síochána Ombudsman Commission say they are investigating last night's fatal collision on the N2 in County Meath.
A woman in her twenties died in the two car collision at Waterside Great, between Slane and Ashbourne.
It is understood a Garda vehicle was pursuing a car involved in the crash.
One woman suffered fatal injuries while two men and two women were taken to hospital but their injuries were not life threatening.
Anyone who witnessed the incident is asked to contact Gardaí at Slane.