The suspected knifeman behind the Jersey massacre had been suicidal over the breakdown of his marriage before the killings of six people including his children, neighbours believe.
Detectives are waiting to question a 30-year-old Polish suspect in hospital over the murders of his wife, their two children and her father.
A family friend and her young child were also understood to be among the victims of the horror attack which has rocked the island.
Neighbours told today how they fended off the "mumbling" attacker with a traffic cone before he turned his knife on himself.
The attack spilled from a flat and into the street yesterday afternoon in an area described by a detective as "one of the safest places in the western world".
One local, who did not want to be named, said the suspect had been rowing with his wife recently and had tried to take an overdose last month.
Another resident in the same block of flats in St Helier said he saw a man chasing a woman with a knife before then stabbing himself in the chest.
Bryan Ogesa, 24, said he and his two friends used a traffic cone to try to defend themselves as the man then came towards them. As he ran away he saw the body of another man lying in the doorway of the flat with a knife sticking out of his back.
Mr Ogesa, who ran outside after hearing screaming, said: "A man was chasing a woman with a knife, it was quite long."
He said he had first seen another woman lying on the ground and had gone to help her as he thought she had simply fallen over.
"She was responsive, but just mumbling," he said. "That's when the guy started coming towards us.
"He was mumbling as well."
Another man, who would give only his first name of John, said he had been in his garden nearby and ran to the scene after hearing a woman scream.
"She shouted 'please help me, please God help me'," he said.
Mike Bowron, chief officer for Jersey Police, called for local communities to remain "dignified and calm" as he said all the victims, who have not been named, were from Poland and four were from the same family.
"Jersey is an incredibly safe place, one of the safest in the western world, and incidents of this nature are exceptionally rare," he said in a statement.
"It makes such a tragedy even more difficult for people to come to terms with, and no-one could fail to be affected by the events that unfolded here yesterday.
"Inevitably, perhaps, such an incident will raise tensions locally and I would appeal to everyone to remain calm and dignified and allow my officers to continue with what is a complex, demanding and difficult investigation."
There will be no "instant answers" as police try to piece together what happened, he added.
Islanders reacted with despair at the killings as large sections of the crime scene, including a grassy wooded area in front of the flats, was cordoned off for forensic teams.
One local said he saw a woman's body on the ground covered in blood and then watched as paramedics carried the bodies of two little girls out of the flat.
He said: "I've never seen so much blood. They were completely limp. The paramedics were crying.
"They were completely drenched in blood, one of the paramedics had to change his clothes."
He said the girls were blonde and were both wearing dresses. He guessed their ages as being around eight or nine and two or three.
Monseigneur Nicholas France, head of the Catholic Church in Jersey, said there was "great distress and anxiety" at the horrifying attack, and that prayers had been offered at a Polish Mass last night for those involved.
Jersey's Chief Minister, Senator Terry Le Sueur, said: "Jersey is a very safe place and events of this terrible nature are very rare. This has greatly shocked the island's community. Many will need support and counselling in the days ahead and we will ensure this is provided."
The 30-year-old man remains under police guard at Jersey General Hospital as inquiries continued to establish a motive.
The alarm was raised just after 3pm by a member of the public reporting a multiple stabbing at a flat at Victoria Crescent, Upper Midvale Road, St Helier.
Five people were initially confirmed dead but a sixth victim - a woman - was later also pronounced dead at Jersey General Hospital.
At the scene, witness Andre Thorpe said: "I saw police come running out with a child, it was a small child. I just saw the legs. They went off in an ambulance.
"When the paramedic came back her shirt was covered in blood. We have quick-response ambulance cars and two pulled up, grabbed a kit and ran inside."
Mr Thorpe also said he saw police taking a dog round various driveways. He added that the area where the incident happened was quite secluded and not on a main road.