WASHINGTON, United States (AFP) – A white gunman was on the run Thursday after fatally shooting at least nine worshippers in a historic black church in a southern US city in what police called a hate crime.

Churchgoers had gathered for a prayer meeting in the Emanuel African Methodist Episcopal Church on Wednesday evening in Charleston, South Carolina when the shooter walked in, sat in the congregation for about an hour, then opened fire, Charleston Police Chief Gregory Mullen said.

America’s latest mass shooting comes at a time of heightened racial tensions in the country, 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.

In Wednesday’s attack, three men and six women were killed and several other people were wounded.

“At this point, we have nine victims in this hideous crime that has been committed,” Mullen told journalists.

“I do believe it was a hate crime.”

Among the dead was the church’s pastor Clementa Pinckney, who was also a South Carolina state senator, fellow politician Marlon Kimpson told US media.

Police said the suspect was a clean-shaven white man in his early 20s. As of 7:00 am Thursday (1100 GMT), he remained at large and officers swarmed the city with the help of helicopters and tracking dogs to try to find him.

Police released security camera images of the suspected gunman — a slender young white man with dark blond or brown hair in a distinctive bowl-type haircut, and wearing a grey sweater.

“He obviously is extremely dangerous,” Mullen said.

– ‘Absolutely bizarre’ –

Jim Curley, owner of AC’s Bar & Grill, which is located a few blocks from the church, said locals were shocked anyone would carry out an attack in the popular tourist area.

“This is absolutely bizarre,” Curley told AFP. “This is really completely out of the blue… We have no idea what the motivation is.”

The shooting’s designation as a hate crime means federal authorities will help with the investigation and could assist in an eventual prosecution.

Officers also investigated a possible bomb threat after the shooting, but several hours later gave the all-clear.

The incident once again brings to the fore broad racial tensions that persist in many US communities, more than five decades after the Civil Rights Act was enacted to outlaw racial and other forms of discrimination.

High-profile police killings of unarmed black men have prompted riots, as well as much soul-searching and national debate in recent months as America grapples with its troubled racial past.

In April, in the neighboring city of North Charleston, a white police officer was charged after a video surfaced of him fatally shooting a fleeing black man, 50-year-old Walter Scott, in the back.

But Curley said the neighborhood’s residents typically get along fine.

“Generally, there’s not a great deal of racial tension,” he said.

– ‘Dastardly act’ –

Charleston is known locally as “The Holy City,” due to its large number of churches and historical mix of immigrant ethnic groups that brought a variety of creeds to the city on the Atlantic coast.

“This is the most unspeakable and heart-breaking tragedy,” Mayor Joseph Riley said.

“People in prayer on a Wednesday evening. A ritual coming together, praying and worshipping God. To have an awful person come in and shoot them is, is inexplicable.”

Officials did not immediately release the names or any details of the victims.

According to its website, the Emanuel African Methodist Episcopal Church is the oldest such church in America’s southern states.

The church was founded in 1816 and in 1822 was investigated for its involvement with a planned slave revolt, the website states.

“The only reason someone can walk in to church and shoot people praying is out of hate,” Riley said. “It is the most dastardly act that one can possibly imagine.”

Because of the shooting, Republican presidential candidate Jeb Bush canceled campaign events that had been planned for Thursday in Charleston.

“Governor Bush’s thoughts and prayers are with the individuals and families affected by this tragedy,” his campaign said in a statement.

Democratic presidential candidate Hillary Clinton, who had been in Charleston earlier Wednesday, tweeted her condolences.

“Heartbreaking news from Charleston – my thoughts and prayers are with you all,” she wrote.

Mass shootings in America have increased, an FBI report released last year found.

Investigators looked at 160 mass shootings between 2000 to 2013. While there was an average of 6.4 incidents in the first seven years of that period, the number soared to an average of 16.4 shootings over the last seven years.

The deadliest of these include the April 2007 Virginia Tech shooting, when 32 were killed, and the December 2012 Sandy Hook elementary school shootings in Newtown, Connecticut, when a total of 27 people died, including 20 children.

Charleston is famous for its cobblestone streets, Southern cuisine and nearby beaches and islands. The city is also known outside the United States for its namesake 1920s dance.