The religious service was led by one Fortunee Mukankusi, 61, also arrested.
Police and local leaders found the group at about 5pm, congregating in a forest located in Gisanga Village, Gisanga Cell, Mbuye Sector.
Worshippers belong to eight different churches; Catholic, Anglican, Seventh Day Adventist, Methodist, Presbyterian, pentecostal, Goshen and Islam.
They had come from different sectors in three districts; Ruhango (Mbuye, Ntongwe, Kinazi), Muhanga (Shyogwe) and Kamonyi (Nyamiyaga, Nyarubaka).
Wellars Kayitare, the executive secretary for Mbuye Sector, who was part of the enforcement team, warned the believers against such prohibited practices.
He reminded them of the Covid-19 risks they are exposing themselves to, but also putting their families and communities at the same risk.
Kayitare advised them to go to churches which were allowed to resume.
"Religious services are not prohibited; however, it is only permitted in places of worship which were allowed to resume and adhering to health guidelines against Covid-19," Kayitare told the group.
Places of worship allowed to resume can only function at 50% maximum occupancy.
"Coming and overcrowding in this forest... you are not doing any good to yourselves; it should be your lives first before anything," Kayitare told the violators.
Last week, eight people, who were part of the group that was found praying in the house in Rubengera Sector, Karongi District, tested positive for Covid-19.
Superintendent of Police (SP) Theobald Kanamugire, the Police spokesperson for the Southern region warned against such prohibited gatherings.
He thanked members of the public, who facilitate the enforcement through sharing of information on those flouting the Covid-19 prevention directives.