Three students arrested over nine church arsons in Alabama started some of the fires as a joke, officials say.
Two 19-year-olds and a 20-year-old appeared in a federal court on Wednesday and were remanded in custody pending a hearing.
One of them, Benjamin Nathan Moseley, admitted arson, court papers say.
The nine arson attacks, at the beginning of February, destroyed five Baptists churches and damaged four. No-one was injured.
Governor Bob Riley said there did not appear to be "any type of conspiracy against organised religion".
"The faith-based community can rest a little easier," he said.
Federal investigators say the first five fires, on 3 February, were started as "a joke [that] got out of hand".
The other blazes, on 7 February, are reported to have been set "as a diversion to throw investigators off".
Agents are said to have traced tyre markings found at some of the churches to Matthew Lee Cloyd's parents, who admitted their son "knew who did it and he was there", court papers say.
The other two suspects, Benjamin Nathan Moseley and Russell Lee DeBusk Jr, both 19, are due to attend a hearing on Friday.
A decade ago, 30 churches with mainly black congregations in south-east US were set alight in suspected racially-motivated attacks. But officials had earlier said that in the February incidents there was no racial pattern.