A woman who was murdered in a flat in Londonderry suffered a "brutal and savage attack", a senior police officer has said.
The body of the woman, who police have yet to identify, was found in the bedroom of a ground floor flat in Harvey Street following a fire at about 04:15 BST on Saturday morning.
Crews from the Northern Ireland Fire and Rescue service attended the property, where the discovery was made.
Ch Insp Anthony Kelly from the Police Service of Northern Ireland’s (PSNI) major investigation team said the victim suffered multiple injuries and believes a weapon was used during the attack.
At this stage, police believe the deceased woman was in her 40s to mid-60s.
"From our enquires so far, we can tell you that the victim suffered an horrific attack and sustained multiple injuries," Ch Insp Kelly said.
"We know this brutal murder has caused great concern but we can assure you we are working at full pace to establish what happened and catch those responsible for this heinous and evil crime.
"You will see an increase in police presence in the city in the coming hours and days."
Ch Insp Kelly appealed to anyone who was in the Harvey Street area between 04:00 BST and 05:00 BST on Saturday and who saw any unusual activity to contact them.
They also appealed for anyone who had CCTV, doorbell or dashcam footage to do the same.
Crews from the Northern Ireland Fire and Rescue service attended the property, where the discovery was made.
Stunned locals
At the scene: Kevin Sharkey, BBC News NI
There is palpable shock here in Derry this evening as details of this murder emerge.
On nearby streets, people are expressing disbelief at the horrific nature of the killing.
There is also a very visible increased police presence around nearby streets.
The police now face two major challenges - to identify the victim, and to find her killer.
There is a big police investigation underway here.
Locals have been stunned to learn of this tragedy in a residential part of the city.
An extensive area around the scene is cordoned off and that is restricting access to Waterloo street.
'Thoughts and prayers'
SDLP councillor John Boyle visited Harvey Street and said it was a "very, very sad scene".
"I think I suppose the only thing I can reflect on is the terrible shock and distress that the local community have experienced when they woke up to this news this morning of the death of this woman and the circumstances she has died in," he said.
"Evidently now, we're in a situation where we have to allow the police service to carry out their investigations."
'Harrowing'
SDLP MLA Mark H Durkan said it was “harrowing and heartbreaking” news.
The Police Service of Northern Ireland (PSNI) said part of nearby Waterloo Street and Chamberlain Street are closed.
Traffic disruption is expected and the area should be avoided.
Investigating officers are asking anyone with information to get in touch with them.
They are particularly keen to view any dash-cam or doorbell camera footage covering the area between 02:00 BST and 05:00.
Sinn Féin councillor Sandra Duffy said the community was in "total shock".
“My immediate thoughts and prayers are with this woman’s family and friends," she said.