Update 3.35pm: The Gardaí have confirmed that three people, including one child, who were critically injured in the crash in Mayo, have died.
They said that two women in their 70s and 40s, and a seven-year-old boy were pronounced dead at the scene. The truck driver was uninjured.
Forensic investigators are at the scene and southbound traffic is being diverted to Ballyhaunis.
Motorists have been asked to avoid the Claremorris Ballinrobe Junction.
Earlier: Two adults and a child have been critically injured in a crash in Co Mayo.
It is understood a car and a truck collided on the N17 Galway to Sligo Road at Lisduff just after midday.
The driver of the truck was not injured.
Gardaí are appealing for witnesses and traffic diversions are in place.