The incident occurred during Wednesday evening worship at Peoples Church, the Salem Statesman Journal reported. A man reportedly used a burning liquid to start the blaze.
One woman was taken to the hospital by her husband but the extent of her injuries was not released. Another woman's clothing was burned but she was not hospitalized.
The newspaper reported witnesses said the liquid, possibly gasoline, was aflame as it came out of a can the man was holding. It was not clear how he had ignited it.
The man was tackled by some worshippers and held until police arrived.
Witnesses said the man arrived at the church in a taxi and had threatened the driver with a knife. In an ensuing struggle, the taxi driver suffered a minor neck injury, police said.