A woman was woken by a hand being held over her face when three men with softball bats invaded her Wainuiomata home.
Detective Senior Sergeant Dave Thornton of Lower Hutt police said three balaclava-clad men broke into the home of the woman, in her 60s, and her husband, in his 70s, in Hine St just before 5am.
''I couldn't imagine a more terrifying thing than being woken up by people carrying weapons and wearing balaclavas in your own home, I imagine you'd be terrified.''
The intruders tied the couple up and stole a small safe containing a ''substantial'' amount of cash.
The woman was assaulted and suffered minor injuries.
Thornton said the man managed to get free and called police.
''The gentleman managed to get free because the offenders didn't tie his legs as he had an injury at the time, so he got up and used crutches to obtain a knife and cut himself free once the offenders left."
Police believe the robbers may have spent some time planning the home invasion and are appealing for anyone who has seen anything suspicious in the Hine Rd area over the last few weeks to contact them.
''Generally these things aren't done on the spur of the moment, there's a bit of pre-planning that goes into them.
''Whether they've been parked up at the address or driving around and someone local has seen them, or anyone has been approached and asked about the occupants.
"We are determined to catch whoever is responsible for this cowardly act, which was clearly targeted at an older couple in their home," Thornton said.
Neighbour Noeline Colman said she knew the couple since they moved in about 40 years ago.
''It's very frightening. I just feel so sorry for them.''
Colman said the street was a nice part of Wainuiomata where these types of things did not usually happen.
She said the first she knew of the incident was when she saw police in the driveway.
The couple were grandparents. The man was retired while the woman sold baking and jams at the local market.
Anyone with information can contact Lower Hutt police on 04 560 2600, or anonymously on Crimestoppers on 0800 555 111.