According to the same source, the agency received at 07:49 on the 6 September, the alert for an incident in Santo Amaro de Oeiras (Lisbon district).
The suspect of stabbing the young man who died this morning in Oeiras was arrested and the young man was identified in the same process, a source from the Lisbon PSP Metropolitan Command told Lusa.
According to that source, the incident, which took place near a fast-food restaurant and a petrol station, had already started in a nightclub in Lisbon at dawn.
"The individuals met again at the beach of Santo Amaro de Oeiras and one of them mortally stabbed another piercing his chest and striking a second young man in the head who was seriously injured," said the same source.
According to the source, the young man who stabbed the victims escaped along with another man, having already been detained by the authorities.
When INEM's car arrived on the scene, he declared the death of a 24-year-old, while another, 22, considered to be seriously injured, was transported to São Francisco Xavier hospital.
On site were two ambulances of the fire-fighters of Oeiras and the emergency medical and resuscitation vehicle of the São Francisco Xavier hospital.