Christchurch mosque shootings: Dunedin on edge as nails on roof mistaken for shots, battery for bomb

The sound of a man hammering nails on a roof spurred a Dunedin resident to report multiple gunshots to police this morning, as the city remains on edge.

A police spokesman said they received a report of gunshots in Andersons Bay about 9am, near Bayfield High School.

"Somebody thought they'd heard gunshots but it turned out to be hammering [nails] on a roof.''

Meanwhile, police are warning people to be more careful about leaving property unattended in public places while New Zealand has a high state terror alert. The call comes after a battery mistaken for a bomb sparked a major police response in Dunedin yesterday.

Sergeant Anthony Bond, of Dunedin said a large battery with ''wires and tubes'' sticking out of it, was left in a corridor at Dunedin's Ministry of Education building in Moray Pl about 2.50pm yesterday.

All staff in the building were evacuated and Moray Pl was closed between Lower Stuart St and Dowling St for a short time.

However, it was later determined the box was a replacement battery for the building's emergency lighting system.

Bond said police were stood down when a Wormald staff member working in the building, came to collect it.

A police spokeswoman urged people to be more careful about what they leave lying around.

''You do have to be really careful about what you leave lying around in this heightened state of security - even if it's things like children's school bags or a gym bag.

''People are on high alert at the moment and they are worried and stressed, and they are more likely to call it in [to police] than they would have in the past.

''We'll definitely be responding to every call that we get.''

Police continue to investigate a bomb hoax that led to the partial closure of Dunedin Airport on Sunday.

A black bag, described as a laptop bag, was made safe by experts from the New Zealand Defence Force.

It is believed the bag was brought into the airport by a person climbing over an external set of fences in Centre Rd between 11.30am and about 6.15pm.