FORTY people are believed to have been killed in shootings at two mosques in the New Zealand city of Christchurch.

The country's prime minister, Jacinda Ardern, confirmed the total and said at least 20 others had been seriously injured.

New Zealand Police had earlier said that four people - three men and one woman - were in custody in relation to the attacks.

Police said they had defused a number of improvised explosive devices found on vehicles after the shootings.

Officers responded to reports of shots fired in central Christchurch at about 1.40pm local time (12.40am GMT), and urged people in the area to stay indoors.

All schools in the city were put into lockdown as the situation unfolded.

Mosques in Deans Avenue and Linwood Avenue were targeted in the attack, but police urged all mosques across New Zealand to shut their doors in the wake of the incident.

Ms Ardern called it "one of New Zealand's darkest days".