Eight children in Cairns, Australia were stabbed to death in a suburban house, reports said, citing local officials. The victims of the stabbing were believed to be aged between 18 months to 15 years, and a 34-year-old woman was also taken to the hospital for a chest wound.

Emergency services were called to the residence where the stabbing took place while police officials investigated the incident. The relationship between the woman and the children could not be immediately established, police said, according to Sydney Morning Herald (SMH).

However, Lisa Thaiday, the sister of the woman who was stabbed, said that the children were siblings. The killings were discovered when a 20-year-old, thought to be related of the victims, returned to the house to find the eight children dead inside and the woman gravely injured.

"I'm going to see him now, he needs comforting," Thaiday said, according to Sky News, adding: "We're a big family... I just can't believe it. We just found out (about) those poor babies."

Police responded to the situation after receiving a call about a gravely injured woman, and subsequently discovered the slain children after searching the house, Sky News reported.

“As it stands at the moment, there's no need for the public to be concerned about this other than the fact that it's a tragic, tragic event," Bruno Asnicark, the officer investigating the matter, said, according to ABC News, adding: “The situation is well controlled at the moment. There shouldn't be any concern for anyone else out of this environment."

The stabbed woman, who was believed to be the children’s mother, was assisting the police in their investigation, SMH reported.

“The crime scene is being locked down. That includes, from me. Nobody goes in there until our forensic people are finished and until we have done that we're not going to be able to clearly establish any relationships,” Asnicar said, according to SMH, adding: “This is not a small job, we're not taking this lightly at all. We don't do that here in the Far North, This will be done to the nth degree and we will cover every angle before this is finished.”

Australian Prime Minister Tony Abbott called the deaths "an unspeakable crime," adding "These are trying days for our country." The killings come just days after the Australian capital, Syndey, saw a gunman take hostages in a cafe, which eventually resulted in the deaths of two captives and the gunman. 

Queensland Premier Campbell Newman added in a statement, cited by Australia's ABC News, that he was "deeply saddened and shocked," by the events.