Nine people were killed including a pastor and state senator when a gunman entered and opened fire at a church in Charleston, South Carolina, on Wednesday.

Charleston Police said the shooting occurred at around 9 pm at the Emanuel African Methodist Episcopal Church, a prominent church in the US, while people were having a Bible study, NBC News reported.

One of those who were killed was Rev Clementa Pinckney, 42, the church's pastor and South Carolina state senator, the report said.

The suspect was still at large as of press time. Charleston Police described him as a white male, about 21 years old, small build, and wearing a grey sweat shirt, blue jeans and Timberland boots.

"This was a hate crime," Charleston Police Chief Gregory Mullen said early Thursday.

US Senator Tim Scott from South Carolina tweeted, "Heart is breaking for Charleston and South Carolina. My prayers are with Emanuel AME and Pastor Pinckney."

He condemned the killing as a "senseless tragedy at a place of worship—where we come together to laugh, love & rejoice in God's name—is despicable & can't be understood."

Mullen said the report that a secondary explosive device was allegedly found at the scene was unfounded.

Mayor Joe Riley said the shooting "is the most unspeakable and heartbreaking tragedy" to have struck Charleston, adding that the suspect is a "hate-filled person."

South Carolina Governor Nikki Haley released a statement to say, "Michael, Rena, Nalin and I are praying for the victims and families touched by tonight's senseless tragedy at Emanuel AME Church."

"While we do not yet know all of the details, we do know that we'll never understand what motivates anyone to enter one of our places of worship and take the life of another. Please join us in lifting up the victims and their families with our love and prayers," she said.

A prayer vigil will be held Thursday afternoon, according to Rev. Norvel Goff, presiding elder of the Edisto District of the state conference of the AME Church.