People are praying for in the Detroit church where her father was once a pastor.
The special vigil at New Bethel Baptist Church began before dawn Wednesday.
The prayers come one day after Stevie Wonder visited the ailing Queen of Soul at her home. The Rev. Jesse Jackson and 's ex-husband, actor Glynn Turman, also visited Franklin, who is seriously ill.
A person close to Franklin, who spoke on the condition of anonymity because the person was not allowed to publicly talk about the topic, told The Associated Press on Monday that the singer is ill. No more details were provided.
The 76-year-old canceled planned concerts earlier this year after she was ordered by her doctor to stay off the road and rest.