Wellington police say whoever damaged a phone box with a home-made pipe bomb could have been seriously injured.
The phone was ripped from the wall and shards of glass sent flying 30 metres by the blast, at about 4.40am on on Saturday in the suburb of Newtown.
Detective Sergeant Donna Howard says the person who set off the device, made of low level explosives, would have to have lit the wick by hand, which would have been very dangerous.