Police in Strabane say the security alert in the town today follows an attempt to kill police officers in Strabane last night.
Superintendent Gordon McCalmont says they believe a device exploded while police were on patrol in the area of Townsend Street shortly after 8.30pm.
He says the investigation is at an early stage, and police have had to ask some residents to leave their homes while they carry out enquiries. While they are unable to go into specifics of the incident at this stage, he says he is confident in saying they are incredibly lucky that the lives of officers and other members of the community were not lost last night.
Reports from the area say there was a gap of up to two hours between the bang being heard and the security operation getting underway.
West Tyrone MLA Daniel Mc Crossan says there are serious questions to be asked.
He has condemned the attack.............
An earlier message from the PSNI says the alert in Townsend Street, which is also affecting the Liskey Road, would last until at least lunchtime.