KEY POINTS:
Police were checking security camera footage last night to try to find those responsible for a series of explosions that disrupted traffic in Christchurch.
A cleaner who discovered one of three makeshift devices, at the busy Christchurch Bus Exchange, suffered cuts to his hands when it exploded, but was not seriously hurt. In each case, a "coke-like" bottle containing a substance believed to be dry ice or liquid nitrogen was left in public places in the central Christchurch area.
Built-up pressure in the bottles had caused them to all explode about 3.15pm.
The other devices were left at the High Street Arcade and at Carlton Mill corner, a retail area on the outskirts of the central city.
Police closed down the bus exchange to search for any further devices, causing long queues of traffic to back up behind police cordons and stranding dozens of bus passengers trying to leave the central city.
Cordons were lifted about an hour and a half later. Detective Sergeant Mark Reid said the devices would have required some scientific knowledge, but he ruled out any serious terrorist-type threat.
