US President Barack Obama has expressed great “sadness and anger” over the fatal Charleston church shooting, using the occasion to address the need for tighter gun control.

US police arrested a 21-year-old white gunman on Thursday (US time) suspected of killing nine people at the historic black Emanuel African Methodist Episcopal Church, in South Carolina.

Mr Obama said the US should again look at how killers get their hands’ on guns, after what he called “senseless murders” in one of the nation’s oldest black churches in Charleston on Wednesday.

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“Now is the time for mourning and for healing, but let’s be clear – at some point, we as a country will have to reckon with the fact that this type of mass violence does not happen in other advanced countries,” Mr Obama said.

“It doesn’t happen in other places with this kind of frequency. And it is in our power to do something about it.”

The president expressed anger about the attack during a press conference after the shooting.

“I’ve had to make statements like this too many times,” Mr Obama said.

“Once again, innocent people were killed in part because someone who wanted to inflict harm had no trouble getting their hands on a gun.”

Charleston Police Chief Gregory Mullen related the attack to racial targeting.

“I do believe it was a hate crime,” Chief Mullen said.

Mr Obama admitted the difficulty of passing legislation, or even addressing the issue of gun control, in a gridlocked Washington of entrenched political interests.

“I say that recognising the politics in this town foreclose a lot of those avenues right now, but it would be wrong for us not to acknowledge it,” he said.

“And at some point, it’s going to be important for the American people to come to grips with it and for us to be able to shift how we think about the issue of gun violence collectively.”

– with AAP