MARKHAM, Ont. -- A 23-year-old man is facing multiple murder charges in an alleged quadruple homicide north of Toronto, police said Monday.

York Regional Police revealed few details about the four people found dead inside a home in Markham, Ont., on Sunday afternoon, nor did they disclose any relationships between the victims or the accused.

But Const. Andy Pattenden said police are not seeking any additional suspects after arresting Markham resident Menhaz Zaman and charging him with four counts of first-degree murder.

"We do believe that the man we have in custody that's now been charged is responsible for these murders," Pattenden said at a news conference held outside the home on Monday morning.

Pattenden said police were called to the home shortly after 3 p.m. Sunday after receiving a 911 call reporting possible injuries.

He said Zaman opened the door to investigators and was taken into custody shortly afterwards, though Pattenden did not say whether Zaman was the one to phone in the report to police.

Officers soon found the four bodies inside, Pattenden said, declining to reveal the cause of death.

He said the victims are three women and one man, but did not provide their names or ages. Information on their identities will be released once autopsies have been completed, he added.

Emmera Riaz, a former long-time basement tenant at the home where the bodies were found, expressed shock at Zaman's arrest.

She said the former engineering student lived at the home, adding her interactions with him over the years were nothing but positive.

"He's such a nice guy all the time," said Riaz.

Pattenden said investigators had been at the home throughout the night and expected to remain there for "quite some time." Yellow police tape surrounded the house on Monday morning as officers combed through the inside.

Pattenden acknowledged the deaths have shocked the local community, noting hundreds of people had come to the scene in the hours since the bodies were found.

"We want to reassure them that we have this person in custody," Pattenden said.

Zaman appeared in court on Monday morning to face the charges.

— with files from Michelle McQuigge in Toronto.