Charleston Church shooting flares up US racial tensions

US racial tensions hit a new high on Wednesday, after a white gunman stormed a black church in downtown Charleston, killing nine people, in what police call a "hate crime." The suspect was still at large on Thursday. Election campaigning has been suspended for the day.

A small prayer circle forms nearby where police are responding to a shooting at the Emanuel AME Church in Charleston, South Carolina June 17, 2015. Reuters/Randall Hill

"This is the most unspeakable and heart-breaking tragedy," Charleston mayor Joseph Riley told news reporters on Wednesday.

Worshippers were attending a prayer meeting in the Emanuel African Methodist Episcopal Church when the gunman walked in and opened fire.

Police said the suspect was a clean-shaven white man in his early 20s. He was still at large on Thursday, despite a massive man-hunt to find him.

The shooting comes at a time of heightened racial tensions in America, after several high-profile killings of unarmed black men at the hands of white police in recent months led to riots and a national debate on race.

"The only reason someone can walk in to church and shoot people praying is out of hate," Riley told reporters.

Because of the shooting, Republican presidential candidate Jeb Bush cancelled his campaign events for Thursday in South Carolina's second largest city, also known as the "Holy City", due to its large number of churches.

Meanwhile, Democratic presidential candidate Hillary Clinton described the news as "heartbreaking" and tweeted that her thoughts and prayers are with the families of the victims.