A man has been arrested on suspicion of triple murder after the bodies of three elderly men, including twins, were found within 24 hours of each other in Exeter.

Detectives said the three men, two aged 84 and one aged 80, whose bodies were found at two addresses a mile apart, had suffered “significant levels of injury”.

Police said there were no active lines of inquiry that gave them cause for concern that there could be other victims, but asked for anyone who had concerns about vulnerable neighbours to check on them or contact the police.

A 27-year-old man was arrested within hours of the twins’ bodies being found after a member of the public raised the alarm.

Detectives said they were still trying to understand the motive for the attacks. They have not established a clear link between the suspect and the victims or between the twins and the third victim.

Police were called by paramedics at about 3pm on Monday to a house in Bonhay Road, Exeter, after the body of a man was discovered there. Anthony Payne, 80, was confirmed dead at the scene. Police are still tracing his next of kin.

At 1pm on Tuesday police were called to a second property, in Cowick Lane, and the bodies of Dick and Roger Carter were confirmed dead at the scene. Their next of kin have been informed.

The 27-year-old man remains in police custody at Heavitree police station in the city.

Supt Matt Lawler, the local policing commander for Exeter, east and mid-Devon, said on Wednesday that police were appealing for anyone who was in the area of Bonhay Road or Cowick Lane between 8am on Sunday 10 February and 1pm on Tuesday 12 February and may have seen anything relevant to contact police.

Asked at a press conference whether it was possible the men had been a victim of “cuckooing”, which involves a criminal taking over a vulnerable person’s home, Lawler said: “This is very early stages in terms of investigation. We must be careful not to speculate.” He added: “We have yet to establish a clear connection between the parties involved.”

Dozens of officers from as far away as St Ives in Cornwall are helping with the investigation. House-to-house inquiries are taking place and CCTV footage is being studied. Forensic teams were at both properties.

DCI Roy Linden, the deputy head of the major crime investigation team, said: “There are several significant common factors between the addresses. In terms of the levels of violence that were used, we’ve decided to link the investigations. There were significant levels of injury with some commonality between the two incidents.

“We are trying to understand why the three individuals were attacked. There are no active lines of inquiry to suggest there are any other victims.” He declined to say if anything had been taken from the properties.

One woman who lives near the Carters said her mother had seen a “scruffy looking man carrying a tool bag” outside the elderly twins’ home just hours before their bodies were discovered.

Police have been asking the twins’ neighbours if they had noticed vehicles parked outside their home and if they had had anything stolen since 10 February.

The pair were directors of an agricultural company called Traycrop from the early 1990s until it was dissolved in 2004. Neighbours have said they were mushroom farmers.

Graham May, who lives close to the twins’ home, said: “I’ve been here most of my life and know they’ve been in the area for the last 20 years.”

A note pinned to the door of the Bonhay Road address, signed AG Payne, read: “Elderly man 80 years of age wants accommodation for himself and his pet cat.” Neighbours said the note had been there for some weeks.

Neighbours spoke of their shock. Matilda, a university student, said: “I met him when I moved in and introduced myself. He was a pretty quiet guy.”