Officials said a man jumped onto the tracks at the Belmont subway station stop on the Northwest Side. He was killed.
Power had to be shut down to the tracks for about two hours. A bus shuttle was being used until 10:30 a.m. for passengers between California and Montrose.
All service had been restored as of 11:00 a.m. Monday.
(The Sun-Times Media Wire contributed to this report. Contributed portions copyright Chicago Sun-Times 2010.)