Police in Northern Ireland say a teenager missing from his home since Sunday may have sustained a head injury when he fell from his bicycle.
Noah Donohoe, 14, was last seen in the Shore Road area of north Belfast at the weekend.
Chief Inspector Gavin Kirkpatrick said they believe that Noah left his home in south Belfast on 21 June at around 5.30pm on his black Apollo mountain bike.
He was wearing a khaki green North Face jacket, grey sweat shorts with an emblem on one leg, a tie-die blue hoodie, Nike trainers with a bright yellow 'tick' and carrying a khaki rucksack.
He was also wearing a black skateboarding helmet.
Inspector Kirkpatrick said Noah was seen on Ormeau Avenue at 5.45pm and then seen on Royal Avenue heading towards York Street a short time after, before being sighted on North Queen Street heading towards the Limestone Road at 5.57pm.
Superintendent Muir Clark urged people to search buildings, sheds and cars for the missing teenager.
He asked local residents to check their clothes lines for missing items because the boy was reportedly without his clothing.
He said he had no reason to believe he was not within a relatively confined area.
No further reports of his whereabouts have been received and the search has concentrated on the wooded area that he was last seen heading towards.
Supt Clark said: "I need to know that all the outbuildings, all the places Noah could take refuge in, have been checked."
An eyewitness said they believe they saw someone matching Noah's description fall off their bike, "possibly sustaining a head injury, in the vicinity of North Queen Street/York Street, but we do not know the specific time", Inspector Kirkpatrick said.
He added: "We believe Noah got back on his bicycle, cycling into Northwood Road where he then abandons all his clothing, as he is seen a short time later cycling while naked. We believe Noah then dropped his bicycle and left the area on foot.
"There have been no further confirmed sightings of Noah since 6.08pm on Sunday."
He said police officers supported by air support unit, police dogs and a tactical support group have been searching the area alongside community rescue service colleagues and local volunteers.
He added that Noah's family and police are very concerned for him as this is "completely out of character".
WATCH: PSNI press conference over missing teenager Noah Donohoe. The 14-year-old was last seen in the Shore Road area of north Belfast at the weekend | Read more: https://t.co/2d7Gu3tTvB https://t.co/YLbkBd80Z2— RTÉ News (@rtenews) June 24, 2020