Police in the US city of St. Louis, Missouri, are investigating a series of arson attacks that have damaged five churches during the past 10 days.

According to local officials, a blaze at a St. Louis church early Saturday morning was the fifth church fire that the city’s Fire Department has responded to in the past 10 days.

The fire scorched the front doors of New Life Missionary Baptist Church, according to St. Louis Fire Department spokesman Garon Mosby.

St. Louis Fire Chief Dennis Jenkerson said that all the five church fires were set on the front doors. However, he added, the fires have caused minimal damage inside the buildings, and no one has been harmed.

Jenkerson noted that investigators from the St. Louis Regional Bomb and Arson Unit and the Bureau of Alcohol, Tobacco, Firearms and Explosives are working with the Fire Department and local police departments to determine if all five fires are related.

The churches are located within a three mile radius from one another. According to police, the first fire was set at Bethel Non-Denominational Church on Lillian Avenue on October 8.

The next three attacks took place between October 10 and 14, targeting New Northside Missionary Baptist Church, St. Augustine Catholic Church, and the New Testament Church of Christ.