A child rescue alert issued in the early hours this morning has been cancelled after three missing children were found safe and well.
The children, who were missing from their home in Co Roscommon with their mother since yesterday, were found north of the border in the Enniskillen area.
Gardai said all concerned were located by the Police Service of Northern Ireland.
Killian Gregg, eight, and his sisters Elisha, six, and Derbhla, two, were with their mother Fiona Gregg, 41.
They were last seen near their home at around 3pm on Wednesday and gardai believed there to be an "immediate and serious risk" to their welfare.
A Child Rescue Ireland (CRI) alert was raised at around 3am in an attempt to trace the children and their mother, from Hawthorn Avenue, Ballyforan.
The alert was called off at 8.40am after they were found by the PSNI.
A senior Garda source confirmed Ms Gregg has been taken into police custody and her children put in the care of social services.
She was arrested under the Mental Health Act.
The four were located after an off-duty PSNI officer spotted them on the forecourt of a petrol station in Enniskillen, Co Fermanagh.
The policeman contacted the PSNI and officers were sent to the scene.
Gardai were then informed.
They had serious concerns about the children's welfare, which prompted them to raise the CRI alert.
This is the second time the alert has been raised since it was established last year.
There are four criteria for raising it: that the child concerned is under 18, there is a serious risk to their safety, there is a reasonable belief that they were abducted, and there is sufficient information available for the public to assist gardai in locating them.