Flames ravaged a historic black church just north of Charleston, S.C., Tuesday evening for four hours as fire crews from two counties battled to get the blaze under control. Wednesday morning the AP, quoting a “federal source,” reported that “preliminary indications” are that the fire was not an arson.

“It’s gone,” local state senator Cezar McKnight told the Charleston Post and Courier, as he watched smoke billow from the roof of the Mount Zion African Methodist Episcopal Church, a modest congregation in the tiny town of Greeleyville. “They don’t know the cause yet, but I am hoping for the best.

The predominantly African American congregation is more than 100 years old. Their church building had previously been burned to the ground in June 1995, almost exactly 20 years before Tuesday’s blaze.

Two young white men with ties to the Ku Klux Klan were arrested in connection with the fire, according to documents from House Judiciary Committee hearings held in 1996. The men were members of the KKK during the time of the burnings, but since renounced their membership, their lawyer said.

“To see the church burned was sad to me, but to learn that the church was burned by hideous acts of others crushed my heart,” the Rev. Terrance G. Mackey, pastor of Mount Zion, said during the hearings.

Fire crews got Tuesday’s blaze under control around midnight, NBC reported, but not before the roof completely collapsed.

Many onlookers on social media speculated that it had been intentionally set, the latest in a number of arson cases at black churches that have broken out since nine people were slain in a hate-fueled shooting at Emanuel AME in Charleston last month.

Pete Mohlin, a meteorologist with the National Weather Service in North Charleston, told the Post and Courier that the Greeleyville area saw a great deal of lightning between 6:30 and 7 p.m. But, he added, there is no way of knowing whether lightning started the fire.

Crews from Clarendon County and Williamsburg County are still fighting the blaze, which Clarendon County Fire Department special projects coordinator Carter Jones described as “heavy” in a tweet.

The Bureau of Alcohol, Tobacco, Firearms and Explosives is also on the scene. The agency is leading investigations of five other fires that have struck Southern predominantly black churches in recent weeks. So far, three of the incidents have been identified as arson or potential arson, but none are confirmed to be hate crimes.

Mount Zion was put in the national spotlight two decades ago when President Bill Clinton toured the site after it was rebuilt in 1996. He presented Mackey with a plaque that read, ‘We must come together as one America to rebuild our churches, restore hope, and show the forces of hatred they cannot win.”

In a speech at the dedication, Clinton recalled the attacks that black congregations have endured throughout history.

“You think about what happened 90 years ago when the other church was built; people might have expected things like a church bombing. That was the time of Jim Crow, and there were evening lynchings in the South,” he said. “… We know that we’re not going back to those dark days, but we are now reminded that our job is not done.”

Clinton’s remark came in the midst a rash of suspicious fires at more than 670 mostly black churches across the South. The wave of attacks led to the formation of a National Church Arson Task Force, which aimed to investigate the fires and prosecute those who started them.

Now, 20 years later, as the nation reels from the massacre in Charleston, the burnings seem to have broken out again.

At least five black churches have been set ablaze in the two weeks since the shooting at Emanuel AME, just a 90 minute drive from Mount Zion. Three of the burnings were thought to be arson. It is unclear whether the incidents are connected.

Church fires are not all that uncommon, according to a 2013 report from the National Fire Protection Association, the trade association that develops fire codes. The group found an average of 1,780 fires per year at churches, mosques, temples and other religious buildings between 2007 and 2011, of which 16 percent were intentionally set. It does not identify how many of the blazes turned out to be hate crimes.

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives says it is investigating the recent fires, but “at this time” has “no reason to believe these fires are racially motivated or related.”

Capt. D.J. Corcoran of the Knoxville Fire Department, which responded to a blaze at the College Hill Seventh Day Adventist Church on June 21, said that the incident there was an act of arson but did not appear to be a hate crime.

In such crimes, the arsonist typically leaves a message to the effect of “this was intended for you,” he told the New York Times, but investigators found nothing of that sort at College Hill.

Still, many are alarmed by the sudden outbreak of fires. On Twitter, the hashtag #WhoIsBurningBlackChurches has been trending for days. The Southern Poverty Law Center, which tracks hate crimes, called some of the fires “suspicious and possible hate crimes.”

Cleveland Hobdy III, pastor at the College Hill church, where bags of dirt and bales of hay were left on fire outside the building’s doors, said he felt horror at the case of arson.

“When I look at this I see, I think of an intention to try to destroy this entire church. It makes it sad. It’s sad either way that someone would put their mind to try to damage a church that’s trying to help people,” Hobdy told local television station WATE.

Churches have long been symbols of freedom and sites of resistance in the African American community. Much of the political organizing and activism of the civil rights movement took place in church sanctuaries and involved religious leaders.

In his eulogy at the funeral of Clementa Pinckney, pastor at Emanuel AME who was slain in the shooting, last Friday, President Obama called the black church, “Our beating heart. The place where our dignity as a people is inviolate.”

But their political and cultural power has also made these congregations targets in high-profile attacks like the 1963 bombing of the 16th Street Baptist Church and in hundreds more smaller and less widely-covered incidents.

The Charleston shooting “was an act that drew on a long history of bombs and arson and shots fired at churches, not random, but as a means of control, a way to terrorize and oppress,” Obama continued in his eulogy.

The NAACP has said that it’s warning black congregations about the threat of fires and urging them to take precautions.

Corrections: A previous version of this article incorrectly said there have been seven fires at predominantly black churches in the past two weeks. The Washington Post has confirmed six cases of fire at black churches, including the one at Mount Zion AME. A seventh fire that was previously included in the count was at a mostly white church in Gibson County, Tenn. In addition, a video previously accompanying this article confused a 1995 fire in Greeleyvile, S.C. for which two men were tried and convicted with a fire there on June 30. which is not at this time being treated as an arson.