A number of police came under attack in Strabane last night while examining a suspicious object in the area.
A group of youths threw stones, petrol bombs and other missiles at the police when they arrived at an industrial estate on the Ballycolman road to examine a suspicious object shortly after 9 p.m. No injuries were reported.
A controlled explosion has since been carried out at the scene and the incident has now been declared a hoax.
Meanwhile, two petrol bombs were thrown at a house in Crumlin, Co Antrim last night while the family were asleep inside.
The incident occurred just before 2.30 a.m. while a husband and wife and their 19-year-old son were asleep.
One of the bombs was thrown at the family car, causing minor scorch damage. The other was thrown at the front of the house, breaking a window and causing scorch damage to a wall and window frame. It was discovered intact in the living room. Police are appealing for witnesses.
As street violence in the North intensifies, US President George W Bush's special adviser to Northern Ireland, Mr Richard Haass, is due to have talks with political leaders later.