Police respond to a shooting at the Emanuel AME Church in Charleston, South Carolina June 17, 2015. A gunman opened fire on Wednesday evening at the historic African-American church in downtown Charleston, South Carolina, a US police official said. [Photo/Agencies]

CHARLESTON, S.C. - Nine people were killed when a white gunman entered a historic African-American church in Charleston, South Carolina, and opened fire, the city's police chief said on Thursday.

One other person was wounded and taken to a hospital, Chief Gregory Mullen told reporters about four hours after the shooting on Wednesday evening.

Describing the shooting as a hate crime, Mullen said: "It is unfathomable that somebody in today's society would walk into a church when people are having a prayer meeting and take their lives."

He also said that an all-clear had been sounded after an earlier bomb threat in the area of the church.