Detectives investigating the murder of a Japanese man during a series of random attacks in Dundalk, Co Louth, have said terrorism is one line of inquiry.
An 18-year-old Egyptian man has been arrested on suspicion of the stabbing murder and subsequent assaults on two local men - one with a knife and one with a fence pole.
Gardai have not established a definite motive for the violent spree in the Avenue Road area around 9am on Wednesday.
How the attacks unfolded
- The series of attacks started when the Japanese man was fatally stabbed on Avenue Road shortly before 9am.
- An Irish man was stabbed a short time later on nearby Coes Road.
- At 9.40am gardai received a report that another local man was attacked with a fence pole at Seatown Place.
- Neither of the two Irish victims sustained serious injuries.
- The suspect was arrested at around 9.45am on Inner Relief Road in Dundalk. He has been detained at Dundalk Garda Station.
Chief Superintendent Christy Mangan said he believed the victims were selected at random and a potential terror link was being investigated.
"A terror attack is a line of inquiry," he said.
"It is certainly a line that we would look at. We will endeavour to establish the suspect's background, who they are and where they have come from and why are they here.
"Those are the very important questions we are endeavouring to ask and answer.
"And as to why the attacks took place, why an innocent bystander going about their work would be attacked in the middle of Dundalk in the morning slightly before 9am."
Mr Mangan declined to confirm whether a potential mental health link was another line of inquiry.
He said the suspect had come into contact with gardai on January 1 when inquiries about his immigration status were conducted.
The senior officer said he believed the teenager was seeking asylum in the Irish Republic.
Mr Mangan said gardai were making efforts to contact the dead man's relatives.
"It is going to be very, very hard for the family," he said.
"They have someone over here working and the next thing they get attacked and killed in a foreign country."
He said the investigation would have an international dimension and gardai would be liaising with the authorities in Egypt.
The Japanese man was aged 24 and had been living in Ireland for a year.
Gardai appealed for anyone who was in the area of the attacks on Wednesday morning to come forward.