Messages of support have poured in from celebrities following the killing of at least 49 people at two mosques in Christchurch, New Zealand, Friday, in what Prime Minister Jacinda Ardern deemed a terrorist attack. Police have since arrested and charged a 'racist' suspect for carrying out one of the attacks, which he also live-streamed.

John Legend went further than most with his comments, calling on President Trump to condemn white supremacy in this country and take concrete steps to combat it here.

In his tweet expressing sympathy for the people of New Zealand, Trump, who has been criticized for equivocating "all types of racism," called the mosque shootings a "horrible massacre." However, he did not characterize the attack as an act of terrorism, as that country's prime minister did.

"The killings in New Zealand are so horrific and heartbreaking," wrote the "Voice" judge and EGOT recipient. "This white supremacist terrorist movement is so destructive here and abroad. We need to unite against it."

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While Legend acknowledged Trump wasn't directly to blame in this case, he believes the president isn't helping matters, either: "His rhetoric has certainly fueled and inspired these killers' sick minds. He needs to condemn this evil ideology and take real steps to fight it."

Meanwhile, New Zealand-born Oscar winner Russell Crowe joined his countrymen in mourning.

In a tweet sent early Friday, Crowe referred to the killings as "senseless, pointless, cruel deaths," adding, "My heart breaks for all the families involved, and for the beautiful people of New Zealand to whose hearts this pain will attach, for a long time."

The "Gladiator" star, who spent his early years in Wellington, closed out his post with the Maori expression "Kia Kaha," which means "stay strong."

Crowded House singer Neil Finn, one of New Zealand's most famous musicians, learned of the attacks from the U.S., where he is on tour with Fleetwood Mac.

"Waking up to awful news from home, the full extent of the horror that unfolded in Christchurch," he tweeted. "So sad for the victims and families, the whole community, all the good people of Christchurch. Our love and thoughts are with you."

Britain's royal family also sent their condolences, including Queen Elizabeth II, the head of state of New Zealand, who released a statement saying she was "deeply saddened" by the violence.

"Prince Philip and I send our condolences to the families and friends of those who have lost their lives," the statement read. "I also pay tribute to the emergency services and volunteers who are providing support to those who have been injured. At this tragic time, my thoughts and prayers are with all New Zealanders."

"Our hearts go out to the families and friends of the people who lost their lives in the devastating attack in Christchurch," read a joint statement from Prince William, Duchess Kate as well as Prince Harry and Duchess Meghan, who recently visited New Zealand during last fall's South Pacific tour. "We have all been fortunate to spend time in Christchurch and have felt the warm, open-hearted and generous spirit that is core to its remarkable people."

It continued, "No person should ever have to fear attending a sacred place of worship. This senseless attack is an affront to the people of Christchurch and New Zealand and the broader Muslim community. It is a horrifying assault on a way of life that embodies decency, community, and friendship. We know that from this devastation and deep mourning, the people of New Zealand will unite to show that such evil can never defeat compassion and tolerance."

Like Crowe, they closed their message with "Kia Kaha."

Prince Charles, who will one day be king and head of the Commonwealth, of which New Zealand is a member nation, released a statement through the press office at his London residence, Clarence House.

"Both my wife and I were utterly horrified to hear of the most barbaric attacks on two mosques in Christchurch, which resulted in the cruel and tragic loss of so many people’s lives," he wrote. "It is beyond all belief that so many should have been killed and injured at their place of worship and our most special and heartfelt sympathy goes out to all the families and loved ones of those who have lost their lives.."

Charles added, "This appalling atrocity is an assault on all of us who cherish religious freedom, tolerance, compassion and community. I know that the people of New Zealand will never allow hate and division to triumph over these things they hold dear."

Jemaine Clement ("Flight of the Conchords," "What Happens in the Shadows"), who is from Masterston, New Zealand, retweeted a Muslim group's plea to stop circulating videos of some of the killings, which were recorded on video by one of the shooters.

"Let's not make it (worse) and help our police and authorities to make it easy for our brothers and sisters in Christchurch," the tweet asked.

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