A man suffered facial injuries when he was slashed during an argument in St Julian's late on Tuesday morning.
The police said the argument broke out in Lapsi Street shortly after 11am and involved a 25-year-old from St Paul's Bay, a 44-year-old man from St Julian's and a 32-year-old woman from San Ġwann.
Officers from the police Rapid Intervention Unit were called to the scene.
The 25-year-old, who was injured, was taken to hospital in an ambulance.
The 44-year-old man is being questioned by the police.