A security operation has been ongoing since Monday on the Ballyquin Road since the discovery of the device.
PSNI Assistant Chief Constable Mark McEwan said: “I can confirm that the device is viable and investigations are ongoing to establish the full circumstances.
“We are treating this as an attack on a member of staff who also serves her community as a part-time police officer.”
First Minister Arlene Foster condemned the attack.
“I have spoken to the police officer who was targeted by terrorists last night in County Londonderry,” she tweeted.
I have spoken to the police officer who was targeted by terrorists last night in County Londonderry. I wanted to convey our support and utter condemnation of those who sought to harm her & her family. Reckless and futile.