By Matt Pearce, Los Angeles Times (TNS)

The NAACP warned black churches Tuesday to take “necessary precautions” as authorities in Southern states investigate whether several church fires over the last week were arsons.

Citing a series of arsons that struck black churches across the South in the 1990s, the NAACP used a Twitter hashtag that went viral this week and tweeted Tuesday, “Almost 20 years later, we must again ask, #WhoIsBurningBlackChurches?”

Hours later, another historically black church went up in flames.

Tuesday’s fire at Mount Zion African Methodist Episcopal Church in Greeleyville, S.C.—about 60 miles north of Charleston—comes 20 years after the same congregation’s church was burned to the ground by men with ties to the Ku Klux Klan.

The Bureau of Alcohol, Tobacco, Firearms and Explosives said it is looking into the fire, whose cause has not yet been determined.

Officials have said two black churches were targeted by arsonists last week in Knoxville, Tenn., where a van was destroyed, and Charlotte, N.C., where a church building was destroyed. No arrests have been made or suspects identified in those cases. Nor has a possible motive been given.

Investigators were also looking into what caused the fires that destroyed black churches in Macon, Ga., and Warrenville, S.C., though officials said they have not found a cause or any evidence of criminal intent in those blazes.

The ATF has taken the lead on investigating the fires in Charlotte and Macon. A spokeswoman told the Los Angeles Times on Tuesday that there was no update on those cases.

Church fires are relatively common in the U.S. According to the most recent data available from the National Fire Protection Association, officials responded to 1,660 fires at religious and funeral properties in 2011, down from 3,500 in 1980.

About 16 percent of those church and funeral-property fires were intentionally set, which equals about five arsons a week, according to the association.

But the specter of black churches burning—especially after the June 17 massacre that left nine parishioners dead at a black church in Charleston, S.C. — rattled many black activists and social media users given the nation’s long history of racial violence against black churches.

A spike of arsons against black churches in the South during the mid-1990s led to the creation in 1996 of the National Church Arson Task Force, which investigated at least 827 arsons, bombings or attempted bombings at religious buildings that occurred between 1995 and 1999. The task force includes the FBI, the ATF, U.S. attorneys, local prosecutors and other federal and state law enforcement.

Of that 827, at least 269 involved black churches, with 185 of those churches located in the South, according to a 2000 report.

“The bulk of the attacks appear to be ‘random’ acts of vandalism, the work of ‘teenagers’ and ‘copycats’ rather than hardened conspirators,” Jim Campbell, an assistant professor of history at Northwestern University, wrote in a 1996 opinion piece for The Times titled “America’s Long History of Black Churches Burning” that was shared widely over social media on Monday.

There were 297 attacks on religious facilities in general in 1996, 208 in 1997, 163 in 1998 and 97 in 1999, according to the task force reports.

(c)2015 Los Angeles Times. Distributed by Tribune Content Agency, LLC.

Screenshot: CNN/YouTube