Police Commissioner Mike Bush said a person is under arrest but the police are not sure if there are other suspects.
"As far as we know (the shootings took place) in two places, a mosque on Deans Avenue and another mosque on Linwood Avenue," Bush said. "We are not sure that there are other places outside that area that are threatened."
Bush said they were "facing a very serious and tragic series of events in the Christchurch area of Canterbury" and warned people to stay off the streets. He asked "anyone thinking of going to a mosque anywhere in New Zealand today to keep from going, to close the doors until you hear from us again," he said.
New Zealand Prime Minister Jacinda Ardern held a press conference for the shooting of two mosques in Christchurch, describing it as "one of the darkest days in New Zealand".
"What happened here is an extraordinary and unprecedented act of violence," he said.
Ardern said that the aggressor has "no place in New Zealand".
"For now my thoughts and I am sure that the thoughts of all New Zealanders are with those who have been affected by their families," he said.
The police stated that they were mobilizing all the resources of the national police to respond to the accident.
Parts of Christchurch were blocked while armed police were deployed after receiving reports of shots being fired in the city center at 1:40 pm. Friday local time
Speaking at CNN, witness Mohan Ibn Ibrahim said he was inside the mosque when filming started and he heard the killer "shoot continuously for ten or fifteen minutes".
"I was in the mosque, mosque and there were more than 200 people inside. The gunmen came from the back. The shots went on for a long time. We had to skip the wall to escape. I saw a lot of broken glass and brick at the back of the mosque, "he said.
"I arrived on the street and saw a person who shot him in the chest," he said, adding that the ambulance and the police arrived on the scene.
He said he had a friend in another mosque in the area told him that an armed man had opened fire there too and five people had died.
"I was unable to contact two of my friends who are in the mosque," he said.
A spokesman for the hospital in Christchurch told CNN that "many" losses had been sent there, but they did not confirm the number.
The police are aware of a video shared online and not verified by CNN which aims to show an armed man walking in a mosque without a name and opening fire.
"The second shot, I run, many people were sitting on the floor," he said. "The gun was (at) the entrance door, I run behind the mosque and I was sitting behind … and I called the police."
According to TVNZ, Nazir saw more deaths and injuries, including three women on the ground outside the mosque
Bush said in a statement that "all Christchurch schools have been put on the block"
"The police are urging anyone in the center of Christchurch to stay off the streets and immediately report 111 suspicious behavior," he added. .
A video posted on Twitter showed the Bangladeshi cricket team leaving the mosque. Speaking at CNN, the team's coach said their bus had stopped at the mosque when it was fired.
Christchurch is a coastal city of 404,500 residents. It is the second most populous city in New Zealand behind Auckland and Wellington. It has an agricultural economy.
In 2010 and 2011, the city suffered a series of devastating earthquakes, with the most destructive at 6.3 magnitude, which killed about 200 people and destroyed thousands of buildings.
This is a developing story.