Armed riot police have dispersed protesters blocking the Orange Order parade in North Belfast.
The demonstrations delayed the parade for 90 minutes.
Police fired a number of baton rounds after being attacked with petrol bombs and used water cannon in an attempt to disperse the crowds.
A police woman was taken to hospital after she was struck on the head by debris thrown from the roof of the shops.
In Portrush, a four-year-old boy was injured when he was hit on the head with a bottle returning from an event.
A 17-year-old boy was arrested after the incident.
Police described the disturbances in Portrush as minor and said the Twelfth parade in the town was otherwise peaceful
Thousands of Orange Order members take part in the annual 12 July demonstrations at 18 centres in Northern Ireland.
Last night, a PSNI officer was shot but not seriously injured in Belfast.
View images of overnight disturbances
The female PSNI officer was shot in the North Queen Street area of Belfast.
Two other officers needed medical attention after more trouble in the Broadway area of the city.
Ardoyne in north Belfast was expected to be tense today as Orangemen seek to march past nationalist homes on their way to and from parades.
In recent years the Orange Order has been attempting to stress the tourism potential of the annual 12 July demonstrations.
It claims that last year more than 500,000 people took part in the parades or enjoyed them as spectators.
Shops in Belfast will open today as the city seeks to send out a message that it is open to visitors.
But the signs are that violence on the margins of a small number of parades will once more be an issue.
