A CTA employee was also hospitalized following this incident, after witnesses said she was overwhelmed by the shooting. Union leaders who represent CTA employees on trains say the transit agency has not been investing enough in its members' safety.

The union for CTA workers is raising concerns about safety and security on buses and trains in Chicago, with members expressing fear of being shot or attacked on the job.

Union leaders now say their members who work for the CTA continue to worry about their safety — to the point where many do not want to come to work. Sabrina Franza reports.