Mourners lined the streets Thursday as a horse-drawn hearse carrying Mayor Bob O'Connor's casket made its way to St. Paul Cathedral, where more than 1,000 people attended his funeral.

"This is a day that we have heavy hearts in the city of Pittsburgh," said the Rev. Terrence O'Connor, the late mayor's son. "Our hearts are filled with sorrow because it's hard to say goodbye to someone who has truly lived his life for others."

Bob O'Connor, 61, died Sept. 1, just eight months after taking office and weeks after being diagnosed with a rare brain cancer.

His son recalled once asking his father why he got involved in politics.

The late mayor responded: "'I just wanted to help people.' It was that simple with my dad," Terrence O'Connor said.

Gov. Ed Rendell, state and local lawmakers, business leaders and Pittsburgh Steelers owner Dan Rooney attended the Mass.

Regenia Chapman, a 77-year-old former crossing guard, waited an hour and a half out the church to pay her respects.

"He started to do things for the city. He gave the impression of making it happen. He had heart," she said.

O'Connor, a Pittsburgh native, was diagnosed in July with primary central nervous system lymphoma. He was hospitalized and underwent chemotherapy and radiation treatments, but neither could stop the cancer's spread.

City Council President Luke Ravenstahl was sworn in to replace him.

During O'Connor's first seven months in office, he spearheaded efforts to clean up the city and promote downtown development.

He is survived by his wife and three grown children. Showing the family's strong ties to the city, O'Connor's youngest son, Corey, planned to attend the Pittsburgh Steelers home opener Thursday night and lead the stadium in a wave of Terrible Towels.