A man has been arrested after a mortar was found during a security alert in Strabane.
The 33-year-old was detained under the Terrorism Act in the early hours of Sunday following the discovery of an improvised explosive device.
Police said the device was a mortar which had been placed on a wall close to homes in the Church View area - and was discovered by a resident.
They believe it was "placed in order to attack police officers at the nearby police station".
A spokesperson for the PSNI said: "This is not the first time a deadly device has been left in a public space recently and serves to remind us all how little the terrorists responsible care for the lives of local people."
Several homes were evacuated while examinations were carried out at the scene, but the alert has now ended and residents have returned home.
Chief Constable Simon Byrne condemned the incident as “another callous attempt to kill or maim our officers”.
He added that it was “a stark reminder why we need to grow (the PSNI) to 7,500 officers to grow our presence in communities to deal with this severe threat”.
Local politicians have also condemned the alert, which had forced pensioners to leave their homes for a time.
Sinn Féin MP Orfhlaith Begley said: "Those behind this alert have nothing to offer the people of Strabane and have no support.
"These actions need to end immediately."
SDLP West Tyrone MLA Daniel McCrossan branded the alert a disgrace, adding: “There is no place for these criminals on the streets of our town.
“They need to get off our streets and get off the back of people living here.”
Police have linked the incident to the hijacking of a delivery driver's car in the Mount Sion area at around 9.40pm on Friday evening.
They said: "A fake order was placed with a pizza outlet from a phone box on Bridge Street and when the driver arrived at the stated address, his orange-coloured Fiat Sedici was taken from him by three men.
"It was subsequently discovered on fire at Evish Road around 45 minutes later.
"I am keen to hear from anyone who saw the orange Fiat in the town or who noticed anything out of the ordinary in the Church View area on Friday night."
Meanwhile the device at the centre of the alert, which police say was "viable", has been removed for further testing.
The Police Federation, which represents officers, praised the efforts of those involved at the scene in dealing with the alert.
It added: “Doubtless, lives have been saved and a vicious attack averted by the actions of our colleagues in Strabane.”