An off-duty policeman was seriously injured and another three were slightly hurt when they arrested a knife-wielding man in Paceville early this morning.
The police said the incident happened on St Rita Steps at about 5.20.
The incident started when the man threw a glass at a group of people.
When one of the policemen identified himself and ordered the man to stop, the man spat at him and produced a knife.
He ran off when the policemen tried to arrest him but was apprehended after a struggle.
Investigations are continuing.