Envi McClin and Montashia Brown were last seen Monday afternoon on the Chrysler Service Drive near Mack Avenue. They went to take out the trash, but they never came back, officials said.
Police believe the girls might be with their maternal grandmother, 53-year-old Wendy Harris, who is also missing.
Montashia, 9, and Envi, 12, went missing around 3 p.m. Tuesday at an apartment complex off Chrysler Drive. Police believe they might now be in the Flint or Detroit area with Harris.
Police want the public to be on the lookout for all three.
Envi is 4 feet, 11 inches tall, with brown eyes and black hair. She was last seen wearing a ponytail with a white headband, a dark blue shirt, a pink jacket, blue jeans and pink gym shoes.
Montashia is 4 feet, 8 inches tall, with brown eyes and black hair. She was last seen wearing her hair in a bun with a red headband. She was wearing a black and white Mickey Mouse shirt, black stretch pants and black and white Jordan gym shoes.
Anyone with information is asked to call Detroit police.