The mayor of Markham, where four people were killed in a home on the weekend, says the city is "in shock" over the violence and he wonders whether anything could have been done to prevent the deaths.

In an interview with CBC Radio's Metro Morning on Tuesday, Frank Scarpitti sought to reassure Markham residents that the city is safe and the residential neighbourhood where the killings occurred is normally a peaceful place.

"When something this horrific happens in a neighbourhood like the one this has happened in, it just goes so much against the grain of what the community is all about," Scarpitti said.

"This is a community where there are lots of young families, hard working people, active youth in the schools and participating in sports. When something like this happens, I think people are in shock."

Menhaz Zaman, 23, was arrested and charged with four counts of first-degree murder in the case and remains in police custody. York Regional Police have yet to release the names of the victims.

The bodies of three women and one man were found in the home.

Scarpitti said the slayings raise many troubling questions.

"I think people probably wonder, knowing and hearing what you have heard of the accused, was there something that could have been done? Had he reached out to someone, a family member or to someone in the community, could this tragedy have been prevented somehow?"

Scarpitti expressed condolences to family members, friends and work colleagues of those killed.

"These are people who are now being missed in so many lives and in so many different circles," he added.

Markham Mayor Frank Scarpitti said his city is struggling to come to terms with the killings. (Barry Smith/CBC)

Police were called to a home on Castlemore Avenue shortly before 3 p.m. on Sunday.

When officers arrived, they encountered Zaman at the front door. He was arrested, then police entered the home and found the four bodies. Police have not said why he was arrested before the bodies were discovered.

Police will release names of dead once confirmed

Const. Laura Nicolle said Tuesday that officers are continuing to collect evidence at the home and that police will release the names of the four people killed as soon as post-mortem exams are finished.

Menhaz Zaman (bottom left) appeared in a Newmarket, Ont. courtroom on Monday. (Pam Davies/CBC)

"There certainly has been some speculation out there about who the individuals are, but from our end, we have to have it confirmed through all the proper channels," she said.

Ammara Riaz, a neighbour who previously lived as a tenant at the home where the bodies were found, told CBC News that Zaman lived in the home with his grandmother, mother, sister and father.

Police have not commented on the cause of death and Nicolle declined to say whether they have recovered a murder weapon.