COMING UP IN JUST A BIT. SO WE'VE GOT SOME PRETTY BEAUTIFUL WEATHER ONCE AGAIN TODAY. >> THANK YOU. >>> LET'S GET TO THAT BREAKING NEWS. WE JUST LEARNED FROM FOREST PARK POLICE THAT FOUR PEOPLE WERE SHOT AND KILLED ON A BLUE LINE TRAIN. >> IT HAPPENED AROUND 5:30 THIS MORNING AND ASAL REZAEI IS LIVE AT THE FORREST PARK CTA STATION WHERE THIS INVESTIGATION IS UNDERWAY RIGHT NOW AND HAS BEEN FOR THE LAST FEW HOURS. YOU JUST GOT THE UPDATE FROM POLICE? >> Reporter: YEAH, AN UPDATE FROM THE LAST TIME I SAW YOU GUYS ABOUT 30 MINUTES AGO, FOREST PARK POLICE NOW SAYING THEY RESPONDED TO A SHOOTING NEAR HERE AT 5:30 THIS MORNING. THEY FOUND FOUR PEOPLE SHOT, THREE OF THOSE PEOPLE WERE DECEASED, PRONOUNCED HERE ON THE SCENE. A FOURTH PERSON WAS TAKEN TO THE HOSPITAL WHERE THEY LATER DIED. THEY SAY THE SHOOTER INITIALLY GOT AWAY. FOREST PARK POLICE WORKING CLOSELY WITH CTA SECURITY WERE LATER ABLE TO TRACK DOWN A SUSPECT THROUGH SURVEILLANCE VIDEO. CPD FOUND THE SUSPECT MATCHING THE DESCRIPTION ON A CTA PINK LINE TRAIN AND TOOK THEM INTO CUSTODY. THEY SAY THEY ALSO RECOVERED A GUN IN THAT ARREST. FORREST PARK DETECTIVES ALONG WITH WEST SUBURBAN MAJOR CRIMES TASK FORCE UNIT NOW TAKING OVER THE INVESTIGATION. THEY SAY RIGHT NOW THEY BELIEVE THIS WAS AN ISOLATED INCIDENT. A NUMBER OF NEIGHBORING AGENCIES HERE ASSISTING THIS INVESTIGATION. ELMWOOD PARK, FRANKLIN PARK, CICERO BERWYN POLICE, ALL HERE ON SCENE. THIS IS A VERY ACTIVE, FLUID SITUATION RIGHT NOW. WE KNOW THE BLUE LINE IS SHUT DOWN BETWEEN AUSTIN AND FOREST PARK HERE. THERE ARE SHUTTLE BUSES ON THE OTHER SIDE OF THE TRANSIT CENTER HERE. THEY ARE HELPING TO GET PEOPLE WHERE THEY NEED TO GO. BE THEY A BUS STOP OR A DIFFERENT TRAIN STATION. POLICE TELL