There is an increased police presence in Londonderry, following the murder of a woman in the city.
The body of the woman, who the police have yet to identify, was found in a flat in Harvey Street at about 04:15 BST on Saturday.
The police have said the victim, who is believed to be in her 40s to mid-60s, suffered a “horrific” death.
According to the police investigation team she was attacked with a weapon before a ground floor flat was set on fire.
Crews from the Northern Ireland Fire and Rescue Service attended the property, where the discovery was made.
At the scene: BBC reporter Kevin Sharkey, in Derry
The “brutal and savage“ murder is casting a shadow over the city this weekend.
At the heart of the community concern is, who was this woman and who killed her?
The fact that the police can only estimate the woman’s age underlines the challenges detectives face as they try to identify the victim.
At this stage the police are unable to confirm what type of weapon was used.
The flat is part of a complex of flats on Harvey Street.
There has been a visible increased police presence in the area throughout the weekend.
The police now need help from the public to identify the victim and to find her killer.
‘Heinous and evil crime’
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.
“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.”
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.