New Zealand, March 15 -- New Zealand police say they have taken into custody three men and one woman over the shootings at two mosques in Christchurch.

Prime Minister Jacinda Ardern called the events Friday afternoon "one of New Zealand's darkest days."

The shootings involved multiple fatalities but authorities have not said how many.

New Zealand Police Commissioner Mike Bush said police have defused a number of improvised explosive devices found on vehicles after the mosque shootings.

A man who claimed responsibility for the shootings left a 74-page anti-immigrant manifesto in which he explained who he was and his reasoning for his actions. He said he considered it a terrorist attack.

Police have warned people to avoid mosques anywh...