A Reuters reporter saw several bodies lying on the stadium grounds as well as several unconscious people. Ambulances and police cars were rushing the injured to hospital.
"The stadium was very crowded, people were standing on the ground as well as the bleachers,” the reporter said.
After the president left, people rushed to get out of the stadium and that's when the stampede happened," the reporter said.
The Ibb province is about 170 kilometres south of the capital Sanaa.
Yemen is due to hold presidential and local council elections on September 20.
Mr Saleh, the poor country's long-serving president and the front-runner in the poll, is touring Yemeni provinces to drum up support for his campaign.