Armed police following a shooting at the Al Noor mosque in Christchurch, New Zealand, March 15, 2019. REUTERS/SNPA/Martin Hunter

WELLINGTON (Reuters) - New Zealand police detained four people on Friday after mass shootings at two mosques in the city of Christchurch.

“Four are in custody. Three are men and one is a woman,” New Zealand Police Commissioner Mike Bush told reporters in Wellington.

“There were a few reports of IEDs strapped to vehicles which we were able to secure,” he said, referring to improvised explosive devices.

He said it was not possible to assume that the attack was isolated to Christchurch, saying: “At this point in time we should never make assumptions.”

New Zealand media have reported that between nine and 27 people have been killed.