Honolulu police said Sunday they were investigating what appears to be the murder-suicide of a family, including three children, at a home in the Manoa neighborhood.

Police first arrived at the home at 8:30 a.m. but left after no one answered the door, Lt. Deena Thoemmes said during a news conference Sunday afternoon. She explained the initial call was from an anonymous person and police had no cause to enter the home.

Officers returned at 9:15 a.m. after receiving another call and were able to speak with a caller. Upon entering the residence, they found four people who’d been fatally stabbed and appeared to be a wife and three children aged 10, 12 and 17. The husband also was found dead.

A preliminary investigation showed the husband fatally stabbed his wife and children, Thoemmes said. When asked whether the husband stabbed himself, she said his cause of death was under investigation.

The ages of the adults wasn’t immediately known. The medical examiner’s office will release the identifications of the deceased.

There was no history of domestic calls to the residence and police didn’t have a motive for the killings, Thoemmes said.

Witnesses reported there had been an argument in the home early Sunday morning, police said.

The five deaths mark the state’s worst mass killings since the “Xerox murders” on Nov. 2, 1999, when Bryan Koji Uyesugi fatally shot seven co-workers, including his supervisor, Honolulu Police Chief Joe Logan said.

The horrific scene found Sunday will have an impact on the officers, Logan said, “as it would any officer, for the rest of their lives.”

Logan went to the scene and met with the distraught officers, as did police department counselors, CBS Honolulu affiliate KGMB-TV reported.

Neighbors told the station the residence was known to be a festive house with decorations during the holidays, but one resident said they noticed that it had no decorations this past Christmas.

Honolulu Mayor Rick Blangiardi issued a statement saying he’s “heartbroken by the tragic incident … claiming the lives of an entire family,” KGMB reported. “This inexplicable tragedy has deeply shaken our community. Our heartfelt thoughts and prayers go out to the families and friends grappling with this profound loss.”