Mayor Bob O'Connor, who learned he had a rare form of brain cancer only seven months into his term, died Friday night, his spokesman said. He was 61.

O'Connor died at about 8:55 p.m. at UPMC Shadyside hospital, where he had been treated since being diagnosed with a rare form of primary central nervous system lymphoma in July, spokesman Dick Skrinjar said.

City Council President Luke Ravenstahl was to be sworn in as mayor later Friday, Skrinjar said.

O'Connor was initially admitted to the hospital after complaining of flulike symptoms. Diagnosed with an ulcer, he was released several days later, but subsequent tests revealed the mayor also had cancer. He was readmitted to the hospital on July 10, and began chemotherapy treatment for four brain tumors.

O'Connor's condition took a turn for the worse earlier this week, when brain scans showed "seizure activity" and tests indicated that his spinal fluid and a drain that had been implanted were infected. He underwent surgery Monday to drain a buildup of fluid.

O'Connor, a former City Council president, became the city's 58th mayor in January. During his first seven months in office, he spearheaded efforts to clean up the city and promote downtown development.

He pledged to restore Pittsburgh's financial stability after succeeding Tom Murphy, whose 12-year tenure saw the city sink to near bankruptcy.