A Japanese man has been stabbed to death in a series of attacks in Dundalk, in the Republic of Ireland.
Two Irish men were also injured in linked attacks in the town, which is in County Louth, just south of the border with Northern Ireland.
An 18-year-old Egyptian man has been arrested and is being questioned by police.
Irish police have said that terrorism is one line of enquiry.
The first attack took place in Avenue Road when a 24-year-old Japanese man was stabbed in the back just before 9am as he was walking to work. He died at the scene.
Two further attacks took place in different locations across the town over the course of the next 40 minutes.
The second victim, a local man, was stabbed in Coes Road.
A third man – who is also local – was hit with an iron post at Seatown Place. Neither man’s injuries are believed to be life-threatening.
The teenage suspect was apprehended around 40 minutes after the first attack took place, carrying a large fence post.
Police believe all the attacks were random and unprovoked, calling the dead man an “innocent bystander”.
Irish police are attempting to contact the Japanese victim’s family to inform them of his death.
Chief Superintendent Christy Mangan said: “A terror attack is a line of enquiry – it is certainly a line that we would look at.”
Chief Supt Mangan said they believed the suspect was acting alone, and reportedly said he may have been “carrying at least two knives”.
He also said they would be investigating the suspect’s background and his reason for being in the country.
The teenager had come into contact with police on New Year’s Day when officers were looking into his immigration status.
It is understood he was seeking asylum in the Republic of Ireland.
Local councillor, Ruairi O Murchu, who lives close to the scene of the fatal stabbing, said: “The community is in shock.”
An autopsy is now under way, and police have appealed to any witnesses to the attacks to come forward.