Police have been given an extra 36 hours to question a 27-year-old man on suspicion of murder following the murder of three elderly men in Exeter.
The deaths of the men, all in their 80s, are being linked because of the "level of violence" used in their deaths, detectives confirmed.
The local vicar, David Nixon said the community was in shock at the events, and prayers would be said for the trio at a special service.
Police said there were similarities in the attacks at a press conference on Wednesday afternoon - but would not be drawn on how the victims died.
The first victim, who was aged 80, was discovered at a property in Bonhay Road on Monday afternoon just after 3pm by paramedics.
Less than 24 hours later - at 1pm on Tuesday, a member of the public became suspicious and called the police to Cowick Lane where they found the bodies of 84-year-old twins, Dick and Roger Carter.
A 27-year-old man has been arrested and is being questioned at Heavitree Road police station in connection with the murders.
He appealed for anyone who had spotted anything suspicious near the two addresses - between 8am on Sunday morning and 1pm on Tuesday - to contact the police.
The families of the two 84-year-old men have been informed of their deaths, while police have yet to find the next of kin of the 80-year-old found in Bonhay Road.
Superintendent Matt Lawler, of Devon and Cornwall Police, said police had increased patrols in the area and were seeking to reassure elderly people.
He said: "This was have concern in our local community, particularly those who feel vulnerable or the elderly. It has obviously shocked the community - and it shocked us.
"Our immediate thoughts remain with the family of the men found dead but I would like to reassure everybody of the significant commitment from Devon and Cornwall Police through the major crime team and specialists across the force to progress this investigation at some significant pace."
He confirmed forensic teams will continue to work at both addresses in the coming days.
Watch the police press conference, as it happened, here: