Charleston church shooting
Mourners hug after praying outside the Emanuel African Methodist Episcopal Church in Charleston, South CarolinaBrian Snyder/Reuters

Prayers are being held across the US to mourn the nine victims of the Charleston gun attack, who died when 21-year-old white gunman Dylann Roof opened fire inside an African-American church in South Carolina.

Outdoor services had to be arranged after many churches in Charleston began overflowing with people. Many cities including Miami, New York, Detroit, and Philadelphia also held services for the victims.

The suspect spent an hour inside the Emanuel African Methodist Episcopal Church, before gunning down six women and three men in what has now been described as a "hate crime" against black people.

The victims who ranged in age between 26 and 87, include a pastor.

Roof was later arrested by the police in Shelby, North Carolina, following a tip-off from a local, after a 14-hour manhunt.

"We really have to fight together to go on and to live a civilised life where race doesn't matter," Martha Watson, who was among the hundreds of people gathered to pay tributes, told the BBC.

Protesters have also been holding placards reading "Black Lives Matter" and "Stop killing black people" — slogans which began doing the rounds following several attacks by law enforcement agencies against black Americans — to condemn the attack.

Governor Nikki Haley, finding it difficult to hold back her tears, said: "We woke up today, and the heart and soul of South Carolina was broken. Parents are having to explain to their kids how they can go to church and feel safe, and that is not something we ever thought we'd deal with."

Many are also debating whether the incident should be treated as a hate crime attack by a lone wolf or be described as an act of terrorism.

A visibly sombre President Barack Obama said: "Now is the time for mourning and for hearing, but let's be clear: at some point we as a country will have to reckon with the fact this type of mass violence does not happen in other advanced countries."