Police in the North are questioning a man after four people suffered stabbing injuries in the village of Caledon, Co Tyrone.
The victims were workmen who tried to protect themselves with shovels, police said. Officers eventually arrested a 20-year-old joiner and seized a kitchen knife. A witness said he had been drinking with a girlfriend and a school teacher home on holidays from Scotland.
Mark Slevin, 23, said: "He seemed like a decent bloke. "It seemed like a really random spree. He just lost it.
"He just walked out the door, said he was going to the shop. "The next thing I looked out the window and there was a lot of police and ambulances."
Two of those wounded were tonight seriously ill in hospital, while the other victims were said to be in a stable condition. The rampage is alleged to have begun in the local village shop. A victim was chased down the street and behind a row of stone terraced houses.
Neighbourhood Watch co-ordinator Tish Vaughan saw the drama unfold.
"I could see a tall man coming down the street backwards with a spade in his hand, he was zigzagging backwards," she said. "Coming for him was a well built tall young man with curly hair wearing a white shirt. I saw this huge knife he had in his hand so I rang the police."
She said one of the victims, a shopfitter, had been stabbed in the shop. Another onlooker said: "He was roaring and shouting so loudly that I thought somebody had hurt him. "I saw a man running away from him up the hill."
PSNI Chief Inspector Tom Sinclair told how his officers intervened amid the terror. "He was walking about with his blood-stained knife in his hand, he was arrested by police using force and handcuffed," Mr Sinclair said.
"We have heard reports that they (workmen) fended him off using shovels although we have not taken witness statements yet."
Caledon, a village of around 400 people about eight miles from Dungannon, was sealed off as forensic evidence experts wearing white boiler suits and masks combed four separate scenes for clues.
At the local Churchill Primary School parents picking up children were concerned by the news and said it had shocked the close-knit local community. Cafes and shops were eerily quiet as gloved and suited scene of crime experts checked the area.
The victims included one local man and three workers from outside the village. Mr Sinclair said police had not discovered a motive yet.
He added: "We were shocked to be called to this crime involving violence. It is scary for the people involved and it was scary for the police officers. "This man was carrying a 10in knife, there were not too many people but there were some workmen working on the main street who may have seen what happened."
It is believed that the arrested man has not come to police attention in the past. The local bar has been closed as villagers come to terms with the violence.