'New Zealand's Darkest Day': Celebs, Politicians, Others Share Heartbreak On Twitter

Political figures, business leaders, celebrities and others used social media to share their grief for the victims of the mass shootings in New Zealand on Friday.  

At least 40 people were killed and dozens injured in the attack at two Christchurch mosques. In one of the mosques, hundreds of worshippers were in the middle of Friday prayers when the gunman opened fire, according to Radio New Zealand. 

Four people have been arrested. 

On social media, people from all over the world came together to send their sympathies to New Zealand and to express rage at the perpetrators: