The players have been told to stay indoors and a planned meeting at the team hotel was cancelled.
Bangladeshi players and team staff arrived at the mosque for Friday prayers as firing was heard and they were warned not to go inside.
The Bangladesh team is reported to have left the bus and fled on foot to nearby Hagley Oval, where it was scheduled to play New Zealand in the Test match starting on Saturday. The cricket board of both countries confirmed that "the team members and support staff groups are safe".
"The players just started running when they heard the shots".
"When I heard that there is a shooting - the sound whats coming".
"Entire team got saved from active shooters", batsman Tamim Iqbal tweeted, per the BBC.
"Just escaped active shooters.Heartbeats pumping badly and panic everywhere", he was quoted as saying by media reports. Soumya Sarkar was also there, and we were all heading to the mosque for prayers.
New Zealand media also said a shooting occurred in a second mosque, Linwood Masjid in the city. In a statement issued online, New Zealand Police said: "Police can now confirm the lock down of schools throughout Christchurch has been lifted". "Clearly what has happened here is an extraordinary and unprecedented act of violence", Ardern said.
"It's obviously early days in a fairly fluid situation (but) it's something that we as New Zealanders have to look at as well", he said.
Mohammed Isam, the Bangladesh correspondent for ESPN, told the BBC he was with the players at the time of the shooting.
New Zealand police commissioner Mike Bush said police had made four arrests in connection with the attack, which included multiple improvised explosive devices attached to vehicles.
"There were bodies all over me", he said.
At least six people were killed after a shooter opened fire in a mosque in Christchurch, New Zealand, according to unconfirmed reports. They were initially barred from leaving the bus but, after several minutes, disembarked and ran through Hagley Park to the ground.
Bangladesh's team were "50 yards" from the mosque, team manager Khaled Mashud said. The people who were the subject of this attack today, New Zealand is their home, they should be safe here.
"Many of those affected might be migrants to New Zealand". "They are in awful and severe mental (distress), they're not feeling well".