"Their bikes were found late this morning near the lake as well, but I'm not sure because I wasn't up there.
"Police and family were all there together when they were found and finding them is a real relief for all the family."
The children were found near Te Ore Ore bridge bordering the Masterton lake about 2pm, after the bikes they were using were discovered a short distance away late yesterday morning.
"The bicycles belonging to the pair were found and shortly afterwards the two children were located as a result of information from the public,'' police said in a statement.
The relative earlier told the Wairarapa Times-Age the two children had been last seen in their beds about 10pm on Sunday.
More than 30 family and friends had been since early Monday morning scouring empty buildings, backyard sheds and likely bolt-holes as far north as Eketahuna and south to Featherston in search of the young brother and sister.
A mounting roll call of helpers were this morning preparing scores of sandwiches to feed the ranks of searchers who were expected to arrive from throughout the region and beyond.
Social media had also been co-opted in the search, the relative said, with several Facebook group pages and innumerable friends and family posting photographs of the children and pleading for their return or reports of sightings.
The relative said the children were keen students who enjoyed school, sports and a had wide circles of friends.
The boy had come to blows with his younger brother last week but peace had been made, while the girl had been in a lot of trouble in the days ahead of their return to school.
"They are close. They might fight but they are close."