Police said a man in his 20s is in custody and has been charged with murder. Additional people — two men and one woman — were detained as well.
Forty-one of the people were killed at Al Noor Mosque, while seven died at Linwood Mosque. One other died at Christchurch Hospital.
Two explosives were also found rigged to a single vehicle. Police were in the process of defusing them Friday evening local time.
The attack is believed to have been livestreamed on Facebook, using a camera attached to a helmet. “Let’s get this party started," a person says as they pull up to a mosque and then open fire on unsuspecting worshippers. As the shooting unfolds, a person can be heard saying, "There wasn’t even time to aim there was so many targets."
Police are urging that the "extremely distressing" video not be shared and have asked for it to be removed.
A apparent manifesto was also posted to Twitter as well as emailed to various media outlets.
Mike Bush, the city's police commissioner, urged people to stay away from mosques in the country and added that the houses of worship should “close your doors until you hear from us again.”
Prime Minister Jacinda Ardern called the incident one of New Zealand's "darkest days."
"My thoughts, and I’m sure the thoughts of all New Zealanders, are with those who have been affected, and also with their families.
She echoed Bush's comments. "Please remain in lockdown. We are potentially still dealing with an evolving situation."
Ardern added: "This can only be described as a terrorist attack."