Man beaten and robbed outside Chicago City Hall

CHICAGO (CBS) -- Four people beat up and robbed a man near City Hall in the Loop early Tuesday.

Police said the 61-year-old man was walking near La Salle and Washington streets around 2:45 a.m., when four people got out of a dark car.

One person stole his money and phone at gunpoint. The robbers then beat him, cutting his head and arm.

One witness said he saw the moment the group attacked the man.

"As soon as I started picking up the phone to call the cops by my window, they immediately started going through his pants. The fourth man jumped out, grabbed whatever the other dude handed him, looked at me for a split second, and then immediately they all started going in the car, jumped in, sped off," he said.

Police said the Fire Department treated the victim at the scene.

No one was in custody Tuesday morning. Area 3 detectives were investigating.