Prime Minister Scott Morrison of Australia said that one of them was Australian.
"It is clear that this can now only be described as a terrorist attack", Prime Minister Jacinda Ardern said, noting that numerous victims could be migrants or refugees.
"I want to assure the public we are doing everything we can to make sure there is no more harm to their communities", Bush said.
I condemn the violent, extremist, right-wing terrorist attack that has stolen the lives of so many innocent New Zealanders as they went about their peaceful practice of worship at their mosques in Christchurch today. "It unites us against extremism, hatred and terrorism, which knows no religion".
At least 49 people were killed in mass shootings at two mosques full of worshippers attending Friday prayers in an attack broadcast in horrifying, live video by an immigrant-hating white nationalist wielding at least two assault rifles and a shotgun. The death toll is now at 49 but may rise.
The police added that there were "multiple fatalities" in the mosque shooting.
New Avengers: Endgame trailer will give you chills
The trailer incorporates scenes from previous Thor , Iron Man and most importantly Captain America movies as flashback sequences. The trailer stinger shows Thor meeting Carol Danvers , who was shown arriving on Earth at the end of Captain Marvel .
Police have warned worshippers not to visit mosques "anywhere in New Zealand".
Police have taken four people into custody - three men and one woman.
Four people are in custody and one is person is on the loose after fatal shootings at two Christchurch's mosques today.
New Zealand's charitable healthcare organization St John said 20 of its ambulance cars and operational vehicles had been working on the scene of a firearms incident. "What has happened here is an extraordinary and unprecedented act of violence", Ardern told reporters.
Ardern asserted in the strongest terms that "it is clear that this can now only be described as a terrorist attack".
"I called the police and ambulance and they said that help was coming". She said the victims were people who had made New Zealand their home, and that the perpetrators had no place in the country.
Many of those who were killed or injured may be migrants to New Zealand, even refugees, she said.
"Police are still treating this incident as ongoing and Christchurch residents are strongly urged to stay indoors and keep safe, and monitor the Police website and social media for further information". The shootings were carried out in two locations - Al Noor Mosque and Linwood Mosque - with one suspect arrested in between the two locations.