Kilkeel lifeboat was also launched and is searching the coastal area around the southern end of Carlingford Lough.
The search for a missing mum of three in Carlingford is continuing today in the north Louth village.
She was last seen alive at 11.30pm in the town on Saturday and her friends issued a desperate appeal. Her mobile is going straight to voicemail.
Gardaí believe the remains are those of Ms Maguire.
As a result of that, searches began of the shore line and the lough itself, in case she had gone into the water.
A body has now been recovered from Carlingford Lough, a sea inlet that forms part of the border between the Republic of Ireland and Northern Ireland - and police believe it is Ruth's.
Ruth Maguire, 30, was one of 32 women on the hen do, but when the women returned to the house in which they were staying after the pub closed they realised she was not with them.
Gardai are treating it as a tragic event and a post-mortem examination is due to take place later.
"Our sympathy goes out to the lady's family".
Gardaí wish to thank the public for their help in this instance, the help of the volunteers and the Coast Guard, and state no further assistance is required.
The 30-year-old - a nurse at Daisy Hill Hospital - went missing from a hen party in Carlingford late on Saturday night.
"Everybody is very shocked here this morning", Kay McKevitt said yesterday.
"They are not in the village long enough to get their bearings".