In a message posted to Facebook, Christchurch mayor Lianne Dalziel has said all government facilities remain on lockdown.
"This is still an active situation, the police are still doing everything that they can to get the situation under control," she said.
"We're not letting people in and we're not letting people out," she said.
Dalziel assured all parents whose children were inside the city's school that they were safe.
"There's a lot of speculation happening right now and all we can do is trust the police to do what they do best," she said.