The son of a couple discovered shot dead in their home is being questioned on suspicion of murder.
Police found the bodies of Bob Seddon, 68, and his wife Patricia, 65, on Friday.
Nic Seddon, 45, was arrested at his home in Seaham, County Durham, the following day, according to sources.
Greater Manchester Police said it was conducting a "dynamic, fast-paced investigation" into the double shooting.
Officers were called to the couple's address in Clough Avenue, Sale, at about 4.35pm following a concern for their welfare. A post-mortem examination confirmed they died of gunshot wounds.
Superintendent Simon Retford said: "There is understandably a lot of interest from both the public and the media about this case and we acknowledge that people will want some answers. We have launched a murder investigation to establish the exact circumstances of what has happened here and why.
"Our investigation will be able to find the answers if it is allowed to run its natural course unhindered by speculation or gossip. People need to trust the police to continue with their investigation. What I can say is that there is no evidence whatsoever that anyone else in the community has ever been under any threat from this incident."
Four months ago Mr and Mrs Seddon escaped with their lives when a car driven by their son plunged into a canal. It was reported that the black BMW hire vehicle hit a brick, left the road and fell into the Bridgewater Canal in Timperley.
Father-of-three Nic Seddon said he smashed his window to escape and then helped pull his 16-year-old nephew to safety.
He told how he swam back to get his father out from the rear of the vehicle as firefighters arrived on the scene. Fire crews rescued them both and then saved the life of Mrs Seddon.