An arson fire at the door of the rectory of the Shrine of St. Joseph Catholic church in St. Louis early on Thursday was the seventh such incident in the area in two weeks, fire officials said.

Federal and local authorities are investigating the spate of fires set at doors of churches with primarily black congregations in the St. Louis area since Oct. 8, and $9,000 in award money has been offered for information leading to the arrest of those responsible.

Thursday's fire at the doors of the rectory, or priest's residence, was reported at 1:34 a.m. and was immediately extinguished, the St. Louis Fire Department said in a statement. The rectory was unoccupied at the time and no injuries were reported, it said.

No one has been injured in the small fires that have damaged two Catholic and five Protestantchurches. Most have primarily black congregations, although local media reported that the Shrine of St. Joseph church has a mostly white congregation.

The first six churches hit by arson were in close proximity to one another: two in Jennings, a suburb, and four in north St. Louis. The St. Joseph church is much closer to downtown than the others.

A prayer vigil on Wednesday night at one of the churches hit by the fires, the New Northside Baptist Church in Jennings, drew more than 200 people including leaders from a number of denominations, the St. Louis Post-Dispatch reported.

Racial tensions in the region have been high since a white police officer fatally shot an unarmed black 18-year-old in August 2014 in the St. Louis suburb of Ferguson, Missouri.

(Reporting by Fiona Ortiz; Editing by Will Dunham)