"Police are responding with its full capability to manage the situation, but the risk environment remains extremely high".
New Zealand police said the shooter is still active, according to a report in AFP.
"They were just outside the mosque about to get off from the bus and go into the mosque when they heard shooting and a lot of people running out and they saw someone wounded in front of them".
Witnesses told local media there were several casualties inside the building.
The incident is said to have taken place at the Al Noor mosque, located in central Christchurch along Dean Avenue facing Hagley Park.
A gunman reportedly opened fire at the mosque, with the former president of the Muslim Association of Canterbury Mohammed Jama saying a man with a gun went into the mosque about 1.40pm on Friday.
The team is in Christchurch to play New Zealand in a third cricket test starting on Saturday.
Soon after they were barred from getting off the bus, the players escaped and ran through Hagley Park.
A witness who has inside the mosque told ABC News that it was very "peaceful, calm and quiet" when the shooting started. There were reports of armed police at a second mosque in the suburb of Linwood.
"When I heard that there is a shooting - the sound whats coming".
Mario Villavarayen, strength and conditioning coach of the Bangladesh cricket team said the players were shaken up, but fine.
"I came to the street I saw one person got shot on his chest", he said, adding that the ambulance and police then arrived on the scene.