Four bodies were discovered in an east-end Toronto home with a sign on the front door that read, "Do not enter, call police."

Keith Delong is a resident of the Toronto home where four people were found dead Wednesday morning. (CBC)

A Toronto police spokesperson said police received a call around 8:20 a.m. Wednesday regarding a "suspicious incident" at 12 Welwyn Ave. in a residential area east of Markham Road.

A man was taken into custody but hadn't been charged with a crime Wednesday night.

Police described the incident as "a case of familial violence" and said no names or causes of death would be released until next of kin are notified.

"A fair amount of violence" was evident at the scene, said Toronto police Det. Sgt. Pauline Gray. She refused to provide details on the relationship between the victims and the man in custody.

A couple in their late 50s or early 60s reside in the bungalow, according to neighbours, who identified them as Keith and Wanda Delong.

Neighbours said the retired couple had two grown children — a son in his 30s named Richard who lived with the couple and a daughter, Elizabeth.

Wanda Delong, wife of Keith, also lives at the home on Welwyn Avenue. (CBC)

Neighbours said a vehicle belonging to the daughter's husband was outside the home in the morning. Another neighbour said he saw police lead a man away from the house in handcuffs.

The man was dressed in clean, "nice clothes" and appeared to break down and cry when he was being arrested by police in front of a nearby mailbox, said Seth Rogers, who has been living next door for about 34 years.

Rogers said he had noticed the man loitering in the area and pacing before police arrived on the scene.

At the police station where the man is being held, a woman who identified herself as his sister said he was the one who found the note when he went to the house to check on his wife, the couple's daughter.

She said the daughter had apparently gone to her parents' house Tuesday evening and that the man in custody grew worried when no one answered the phone there.

"The whole family were good people, so I don't understand this," said the woman, who added the family was having money troubles.

Along with the home on Welwyn Avenue, police have also sealed off a house in Whitby, Ont., belonging to the Delong's daughter and her husband.

'Lovely' people

Neighbours described the couple as "lovely" and "quiet" people and said they were to depart for Mexico on Wednesday.

Toronto police investigate at a house on Welwyn Avenue, where as many as four bodies were found on Wednesday morning. (CBC)

"I cannot believe this, that someone would do something like this to a family like that," said Peter Lemonides, who was supposed to watch their house while they were in Mexico helping a gravely ill relative. "They were such a good family. It's not fair."

Police and officials with the forensic identification team were still inside house, which is already adorned with Christmas decorations, Wednesday afternoon.

The CBC's John Lancaster, who was reporting from near the house, said it didn't appear that police were looking for any other suspects in the area. Only a police command centre vehicle and a few squad cars remained on the site by the afternoon, he said.

Police have spoken with neighbours living on the street, and one neighbour told CBC News that people were being asked whether they had heard gunshots the night before.

Police are asking area residents not to speak to the media because it could compromise the investigation, Lancaster said.

With files from the Canadian Press