British travellers to New Zealand were today warned to “remain vigilant” following deadly mass shootings at two mosques in Christchurch.

Early reports suggest there have been multiple fatalities in what the country’s prime minister Jacinda Ardern described as “one of New Zealand’s darkest days”.

At least 49 people were killed and 48 injured in the terrorist attack.

All schools in the city were in lockdown amid reports that up to 60 people had been injured with the shooting lasting for 20 minutes.

Police earlier cleared Cathedral Square, where thousands of children were holding a rally for action on climate change.

The targets were the Al Noor and Linwood mosques in the city.

Police Commissioner Mike Bush said: “Police are responding with its full capability to manage the situation, but the risk environment remains extremely high.

“Police recommend that residents across Christchurch remain off the streets and indoors until further notice.”

He confirmed that three men and one woman had been taken into custody.

The Foreign and Commonwealth Office issued an updated travel advisory saying:  “There has been a series of shootings in multiple locations in Christchurch.

British nationals in the area are advised to remain vigilant and follow the advice of local authorities.

“The British High Commission in Wellington is in contact with the New Zealand authorities and urgently seeking further information.

“Anyone worried that a British national may have been affected should call the New Zealand Police hotline: (+64) 0800 115 019 from within New Zealand or register with the Restoring Family Links (RFL) website from overseas.”