Federal investigators are looking at a series of recent fires at black churches in southern states, with three under investigation as arsons.

Investigators from the Federal Bureau of Investigation (FBI) and the Bureau of Alcohol, Tobacco and Firearms (ATF) have not ruled out the possibility of a hate crime in two of the fires, but have said they have no reason to suspect such a motivation in two other cases.

An ATF spokesman, Michael Knight, told the Guardian that the agency is using its Bomb Arson Tracking System database “to track any similar patterns and consistencies” among the fires in recent months. Knight said the investigation includes three fires in Tennessee that took place before the shooting deaths this month of nine black people at a church in Charleston, South Carolina.

The most serious fire, which caused major damage to the Briar Creek Baptist Church in Charlotte, North Carolina, took place in the early morning hours of 24 June.

Senior fire investigator David Williams said in a statement that a taskforce run in conjunction with the FBI and ATF is developing a list of suspects in that case. The department said the taskforce was looking “for burn patterns and digging through debris in order to find the cause”.

The fire is estimated to have caused more than $250,000 worth of damage.

Representatives for the ATF’s Nashville field office and Charlotte fire department said they could not provide further detail, citing the continuing investigation.

A law enforcement official speaking on condition of anonymity told the Associated Press that the fire appeared to have been set by vandals, and that investigators found no evidence that the arson was racially motivated.

Another fire was reported on 21 June at the College Hill Seventh Day Adventist church in Knoxville, Tennessee.

Captain DJ Corcoran of the Knoxville fire department said that the church fire is being investigated “as a set fire, an arson fire, but not as a hate crime”. Corcoran said that some hay alongside the brick building was burned in addition to an unmarked van, and that “it looked more like an opportunist just came upon it, there’s no indication it was anything” other than vandalism.

In Macon, Georgia, the ATF joined an investigation into a fire at God’s Power Church of Christ, said Nero Priester, a spokesman for the field division in Atlanta. Fire sergeant Ben Gleaton told the local Telegraph that the fire was ruled an arson.

FBI special agent in Charge Britt Johnson told the Associated Press that authorities have not ruled out the possibility that the 23 June fire could be a hate crime, but Gleaton told the local paper “we are not seeing anything at this time that’s pointing us” toward that conclusion.

Priester said the ATF performs initial investigation for all fires in Georgia.

Other fires around the south have been ruled out as arsons but raised fears nonetheless in the aftermath of the racially motivated murders of the church shooting in Charleston.

In Warrenville, South Carolina, investigation into a fire at the Glover Grove Missionary Baptist church on Friday has been passed to the state’s primary law enforcement agency, known as Sled.

Captain Eric Abdullah of the Aiken County sheriff’s office told the AP that investigators had not yet determined a cause of the fire. A representative for Sled did not immediately respond to a request for information.

At Greater Miracle Apostolic Holiness church in Tallahassee, Florida, investigators suspect electrical wiring started a devastating fire on 26 June, after a tree limb fell and exposed live wires.

In Gibson County, Tennessee, an ATF agent joined the local fire marshal to investigate the fire that burned down the Fruitland Presbyterian church on 24 June. The county fire chief, Bryan Cathey, told ABC affiliate WBBJ that the fire may have been caused by lightning.

Although authorities have said there is as yet no reason to link any of these fires together into a single overarching investigation, the spate of incidents has fanned fears of resurgent violence against black people. African American congregations have been the victims of arson and vandalism at their churches for decades, particularly in the 1950s, 60s and the mid-1990s, when churches in Tennessee, Alabama, Delaware and Oklahoma were attacked.

More recently, three white men set fire to a largely African American church in Massachusetts after Barack Obama was elected president.