Police in New Zealand filed a terrorism charge against a man accused of opening fire on two mosques in Christchurch, killing 51 people in an attack that led to changes to the country’s gun laws.

New Zealand Police Commissioner Mike Bush said in a statement Tuesday that Brenton Tarrant has been charged with engaging in a terrorist act in the March 15 attack on the two mosques.

An additional murder charge and two additional attempted murder charges have also been filed against Tarrant, bringing the total murder counts to 51 and the attempted murder counts to 40, Bush said.

One of the victims, a Turkish man, died of his injuries in early May after being in intensive care, bringing the deaths to 51, officials have said.

Police said they met with victims' families and survivors of the attack to inform them of the new charges. Police said around 200 people attended the meeting in Christchurch.

The New Zealand prime minister’s office and other agencies were sent a manifesto thought to have been written by the attacker minutes before gunfire was reported. Prime Minister Jacinda Ardern has said it did not contain specifics that could have been acted upon.

In the wake of the shootings, which Ardern called one of the nation's "darkest days," the country’s parliament passed changes to its gun laws.

Tarrant posted a livestream of the attack on Facebook.

In response, world leaders led by French President Emmanuel Macron and executives from Facebook, Google, Twitter and other tech companies gathered in Paris to compile a set of guidelines dubbed the "Christchurch Call," the Associated Press reported.

The U.S. White House did not endorse the global pledge to step up efforts to keep internet platforms from being used to spread hate, organize extremist groups and broadcast attacks, citing respect for "freedom of expression and freedom of the press."

The White House said that it stands with the international community in condemning terrorist and violent extremist content online in the strongest terms," but added that it is "not currently in a position to join the endorsement."

In an op-ed in The New York Times, Ardern said the "Christchurch Call" would be a voluntary framework that "commits signatories to counter the drivers of terrorism and put in place specific measures to prevent the uploading of terrorist content."