Chicago police are advising CTA Green Line riders to stay alert after two robberies were reported at the California station, 200 N. California Ave., in August.

In both incidents, two men forcefully took property from the victims before running away, Chicago police said. In one of the robberies, one of the suspects flashed the butt of a handgun at a witness who tried to chase them.

The first robbery happened about 9 a.m. Aug. 4, police said. The second one happened about 4:30 p.m. Aug. 15.

Anyone with information about these robberies is asked to call Area Central detectives at 312-747-8380.