Gardaí investigating the fatal stabbing of a young man in Co Waterford in the early hours of Thursday morning have formally launched a murder investigation following receipt of postmortem examination results.

Jack Power (25) from Brownstown in Dunmore East was pronounced dead shortly after arriving at University Hospital Waterford early on Thursday morning and a post-mortem by Deputy State Pathologist, Dr Michael Curtis has confirmed he died as a result of a stab wound to the chest.

Mr Power was fatally injured at a house at Shanakiel at around 3.40am and locals in the estate performed CPR on him when he collapsed outside the house as they waited for emergency services to arrive and take him to hospital.

Gardaí are investigating unconfirmed reports that Mr Power had gone to the house in the Shanakiel area with two other young men over concerns about growing anti-social behaviour in Dunmore East including a number of break-ins to cars in the fishing village.

The scene where Jack Power (25) was stabbed at Shanakiel, Dunmore East, Co Waterford. Photograph: Dylan Vaughan

Gardaí are trying to establish the exact sequence of events with some reports suggesting that Mr Power was speaking to a woman in the house when he was attacked by a young man who stabbed him once in the chest. It is believed he staggered from the building before collapsing.

It is understood an occupant in the house contacted gardaí to report an incident in which he claimed an intruder had entered the house and gardaí are trying to establish if there is any substance to that report as part of their investigation.

Gardaí arrested a 17 year old youth at the scene and he is currently being detained at Waterford Garda Station under the provisions of Section 4 of the Criminal Justice Act 1984 which allows gardaí detain suspects for up to 24 hours.

Gardaí also cordoned off the house in Shanakiel and members of the Garda Technical Bureau travelled from Dublin to begin a forensic examination. It was unclear on Thursday evening whether they had recovered any weapon which might have been used in the fatal assault.

According to an informed garda source, the exact sequence of events is in dispute which is why gardaí are particularly anxious to speak to anyone who may have witnessed the fatal assault or may have any information that can assist them.

They have also begun door to door inquiries in the Shanakiel estate and have begun searching for CCTV footage or footage from any cars in the area with dashcams which might assist them in terms of establishing what exactly happened in the run up to Mr Power’s stabbing.

A fisherman, Mr Power is the eldest of three sons of local fisherman, Richard Power and his wife, Loretta. It is understood Mr Power Snr and his second son, Ben were fishing on their boat, The Girl Geraldine off the south coast when they learned of the tragedy.

Local Sinn Féin Cllr Pat Fitzgerald received a call about the attack shortly after it happened and visited the scene. He said tension had been building in the area in recent months over anti-social behaviour but no one ever expected to wake up to news of a killing in Dunmore East.

“I suppose a lot of people heard around six o’clock this morning that Jack had passed away so they heard it before it broke on the news but it’s still shocking – nobody expected to wake up in Dunmore East this morning to hear that a young man had been killed – people are just shocked.”

Gardaí­ are appealing for witnesses, particularly anyone who was in the Shanakiel area of Dunmore East in the early hours of Thursday morning to come forward and contact the incident room at Waterford Garda Station on 051-305300 or the Garda Confidential Line 1800 666 111.