In each case, the suspects approached someone and took their possessions and vehicles by force, Chicago police said.
An incident happened about 11 p.m. May 5 in the 300 block of East 26th Street, police said. Another took place at 3:25 a.m. May 7 in the 3100 block of South Martin Luther King Drive.
In one case, the carjackers implied they had a handgun before committing the robbery.
Anyone with information was asked to call Area Three detectives at (312) 744-8263.