The man was attacked at around 2am after he went outside to investigate suspicious noises. "We strongly believe this was a terror attack," police spokesman Micky Rosenfeld said.
His partner witnessed the assault from a window and escaped from a back door of the house.
The Israeli news website Ynet said the woman was lightly injured when she tripped on barbed wire while running away and later underwent surgery. According to the reports, the dead man was a reservist colonel in his fifties.
The woman, identified as Monique Mor, spoke to Channel 10 TV from a hospital bed.
"Everybody knew him: he was a military man for many years," she said.
The man, identified by the reports as Seraiah Ofer, had served as commander of the Gaza district and in several elite combat units, she said.
Israeli president Shimon Peres issued a statement condemning the killing of a senior officer "who served his country and people".
"No-one will rest until the murderers are brought to justice," he said.
The military stopped short of calling the assault a terror attack, saying an investigation was still under way. It said troops set up roadblocks and searched the area, and five suspects were later arrested.
It was the latest violent attack in the West Bank in the past few weeks.
Last week, a nine-year-old girl was wounded in a suspected Palestinian attack while playing outside her home, and last month an Israeli soldier was shot and killed by a sniper in the West Bank city of Hebron.