ABC News' Nitya Venkataraman and Teddy Davis Report: Rep. Stephanie Tubbs Jones, D-Ohio, died of an aneursym at 6:12 pm ET on Wedneday, according to Tubbs Jones spokesman Joe Hewitt. The congresswoman suffered a hemorrhage caused by an aneurysm while driving her car in Cleveland Heights, Huron Road Hospital staff said.
Huron President Gus Kious said the aneurysm "burst in an inaccessible part of her brain".
Kious said the emergency medical team arrived on scene Tuesday night and acted quickly to move her to the hospital "where she was unstable and in critical condition throughout the night" until she passed away late Wednesday.
The congresswoman was ound "unconscious behind the wheel of a moving car," according to Cleveland's WOIO.
Tuesday's condition followed a full day of activity, including planning for an upcoming discussion on electoral reform, scheduled for Sept. 4, 2008 at Cleveland State University.
Tubbs Jones, a top supporter of Sen. Hillary Clinton, D-N.Y., during the Democratic primaries, was scheduled to travel to Denver on August 24, 2008 to attend the Democratic National Convention as a superdelegate.
In a June interview with ABC News' Kate Snow, Tubbs Jones spoke of the sisterhood she shared with Clinton and the significance of her presidential candidacy.
"It is significant that Hillary Clinton is a woman. It's not the bulwark upon which she runs, but it's significant that young girls across this country have an opportunity to look at Hillary Clinton and say, I could be president," Tubbs Jones said.
She continued, "Regardless of what we talk about, women have a different way of managing. This is my 26th year in public office and we have an opportunity to be much more inclusive, in my opinion, than many of my male colleagues, who I love and who I work with."
Elected to the House of Representatives in 1998 and winning her district unopposed in 2004, Tubbs Jones was the first African-American woman to represent Ohio in Congress. She was 58.
Capitol flags will be lowered to half staff before nightfall.
ABC News' Dean Norland contributed to this report.