Two teenagers aged 18 and 19 have been arrested by police investigating the assault of a man thought to have been seriously injured after stepping in to break up a fight.
Danny Payne, who is in his 30s and from the Clooney estate, was assaulted by a number of men in Newmarket Street in Derry shortly after 2am.
It is believed the former Foyle Search and Rescue volunteer stepped in to try and break up an altercation beside the City Walls when he was attacked.
He suffered serious head injuries and was rushed to Altnagelvin Hospital. His wife Sarah was also injured in the attack.
A 18-year-old woman and 19-year-old man are in a police custody helping investigators with their enquiries.
Mr Payne was transferred to the Royal Victoria Hospital on Sunday afternoon afternoon. The Belfast Trust said he remained in a critical condition.
Police have directly appealed to a man and woman who were in the area to come forward as they may be able to assist police.
Detective Chief Inspector John Caldwell said: “The man was wearing a coat and T-shirt - both dark in colour - and blue jeans while the assault was taking place in Newmarket Street. However, directly following the assault, he was seen walking in William Street not wearing his coat.
"At this stage a large tattoo was clearly visible on his left forearm.
“The woman has long, dark coloured hair and was wearing blue jeans, brown shoes and a three-quarter length green coat.
“I would like the couple, or anyone who recognises their descriptions, to contact detectives in Strand Road on 101 quoting reference 209 22/10/2017 as soon as possible.
"Or, alternatively if someone would prefer to provide information without giving their details they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.
“Police would like to thank members of the public for their patience and ask them to avoid the area if possible while the investigation into this serious assault continues.”