Nine people were shot to death during a prayer meeting inside one of Charleston's oldest and most well-known black churches Wednesday night in one of the worst mass shootings in South Carolina history.

A bomb threat complicated the investigation and prompted authorities to ask nearby residents to evacuate as officers scoured the area for the gunman responsible for the carnage inside Emanuel AME Church at 110 Calhoun St. At least one person was said to have survived the shooting.

Police revealed no motive for the 9 p.m. attack, which was reportedly carried out by a young white man. Charleston Police Chief Greg Mullen said, “I do believe this was a hate crime.”

Mayor Joe Riley called the shooting “an unspeakable and heartbreaking tragedy in this most historic church.”

“An evil and hateful person took the lives of citizens who had come to worship and pray together,” he said.

Authorities did not identify the dead.

State Sen. Clementa Pinckney is the church's pastor and was believed to be inside the 19th century building during the shooting. Pinckney could not be reached later in the night and there were unconfirmed reports that he and one of his relatives were among those shot.

Riley said city police were being assisted by sheriff's deputies, the State Law Enforcement Division and the FBI.

Church members were gathered for a prayer meeting when gunfire erupted. Police spokesman Charles Francis described the suspect as a 21-year-old white male in a gray sweatshirt/hoodie and jeans with Timberland boots. He has a slender build.

Though information was scant, the scope of the tragedy quickly became apparent. Dozens of law enforcement officers, several carrying military-style rifles, fanned out across the area as a team of coroners arrived. Several crisis chaplains also rushed to the area.

Police and emergency vehicles swarmed several blocks surrounding Henrietta and Calhoun streets, just east of Marion Square. Barricades blocked off several streets to traffic, and police asked nearby residents to leave their homes.

Helicopters circled overhead and officers with dogs searched nearby properties.

State Sen. Marlon Kimpson, D-Charleston, said he is praying for Pinckney and for “our Mother Emanuel AME church,” as it's affectionately called by many parishioners. It is the South's oldest black congregation south of Baltimore.

“I ask the nation to keep Charleston in our prayers,” he said.

Gov. Nikki Haley said her family also was praying “for the victims and families touched by tonight's senseless tragedy.”

“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,” she said. “Please join us in lifting up the victims and their families with our love and prayers.”

Outside Medical University Hospital, the area trauma center where the wounded were taken, Jon Quil Lance stepped away from the building to smoke a cigarette and gather his thoughts about his grandmother, Ethel Lance, who he'd heard was shot in the church.

“I'm lost, I'm lost,” he said. “Granny was the heart of the family.” He said his grandmother had worked at the church for more than 30 years.

“She's a Christian, hardworking; I could call my granny for anything. I don't have anyone else like that.” He said he didn't know her condition. “I don't even know if she's alive now.” He threw his hands up. “I don't even know if my grandmother is alive.”

He paced up and down Ashley Avenue, and his thoughts gathered momentum. “What was this guy thinking? That dude shot a bunch of elderly people! Now people are going to be afraid to go to church. I don't know what's going to come of this. I'll tell you this, I'm not the only one praying tonight.”

Back at the scene, crowds of onlookers gathered outside a hotel and a gas station just up the street from the church to watch the police activity on the a hot, humid night.

A few impromptu prayer circles emerged, and rumors quickly spread through the crowd about the death toll.

A white male was briefly detained at the Shell gas station at Meeting and Calhoun streets. Two loud pops were heard and a crowd of people rushed to the front of the gas station where they had the male on the ground and were handcuffing him.

The white male had on a backpack and was carrying a camera and recording device fell on the ground near where he was detained.

David Corrie, 21, of Ladson, said he was walking out of the store and the officers forced him to get down.

He said the officers told him they were just doing their jobs, and he fit the description.

Pinckney was in Columbia earlier in the day for the Legislature's continued session but returned to Charleston and was in the church for a service at the time of the shooting, a Statehouse Democratic caucus member said.

Pinckney, 41, was elected to the S.C. House of Representatives in 1996 at the age of 23.

In 2000, he was elected to the state Senate at 27.

His Senate district includes southern Charleston County and parts of Jasper, Beaufort, Colleton, and Hampton counties.

The Rev. Joe Darby, former longtime pastor of Morris Brown AME several blocks away, was at his Charleston home when he heard the news.

He rushed to the Embassy Suites Hotel around the corner from the shooting to join fellow church members in his district. Darby now is presiding elder of the 33 churches in the AME Church's Beaufort District.

By 11 p.m. Wednesday night, he still had no news about who had been shot and whether Pinckney was among them.

Normally eloquent and outspoken, he was at a loss to describe what happened. “We just don't know,” he said softly.

As the shock of the shooting began to sink in, Riley said, “I know I speak to all the citizens of our community as I express my most heartfelt condolences to the families and friends of the Emanuel AME church members who were killed tonight. We will comfort and support them as we work through this time of great heartbreak.”

Tony Bartelme, Fred Rindge and Andrew Knapp contributed to this report.