A Chicago man was charged today with pistol-whipping a CTA train passenger and stealing his iPhone in an altercation last month that ended with four members of the Guardian Angels volunteer security patrol being stabbed.



Keith Gunn, 34, is accused of attacking a 27-year-old Edgewater man aboard a Red Line train on May 15 as it pulled into the Clark and Division stop, Assistant State's Attorney Terry Clancy said.



The Angels volunteers saw the robbery and were waiting for Gunn as he ran from the train onto the platform, one of the men told the Tribune a day after the incident.



The four witnesses wrestled Gunn to the ground, but his accomplice pulled a knife and stabbed them before he and Gunn ran out of the station, Clancy said.



Photos from surveillance cameras in the station show Gunn and the other suspect then running from the platform, Clancy said.



Three of the Angels and the man who was robbed of his iPhone were treated and released from hospitals, while the fourth Angel wasn't hospitalized, according to court records.



Gunn was arrested Thursday at a relative's home in Rockford. His accomplice is still at large, authorities said.



Gunn, of the 5800 block of West Midway Park, has been convicted of several crimes in the past two decades.



In 1994, when Gunn was 16, he was convicted of murder and sentenced to 20 years in prison, according to court records. He was released from prison in August 2003, a state corrections official said.



Since 2004, Gunn has been convicted of four drug felonies, court records show.



Gunn is charged with armed robbery and aggravated battery in the CTA case. He was ordered held in lieu of $600,000 bail.



Tribune reporter Rosemary Sobol contributed.



rhaggerty@tribune.com