It appeared the forces were mostly firing over the heads of demonstrators, who pushed and shoved in a panic to get away.
Witnesses said they saw several people lying on the ground when the tear gas cleared.
"When we heard the gunfire, I tried to flee. There was chaos and people fell on each other," Abdullah said.
Thousands of women participated in demonstrations in Yemen's conservative capital of Sanaa a startling move in a deeply tribal society where women are expected to stay out of sight. Women have begun turning out in real numbers for the past week, and Friday's turnout was their biggest by far.
In a sign that the Yemeni government was trying to quell the demonstrations, the Internet was slowed to a crawl and phone connections were spotty.
Saleh, an ally in the Obama's administration's fight against al-Qaida, proposed on Thursday night that the government create a new constitution guaranteeing the independence of parliament and the judiciary. That didn't stop protest organizers telling their leader of 32 years that they rejected his offer and want him to go.
The demonstrators in the capital carried the body of a man killed by security forces Wednesday and shouted "The martyr wants the regime to fall!"
Several thousand pro-Saleh demonstrators gathered in a nearby downtown square, shouting slogans in favor of the president's proposed reforms.
Yemen was chaotic even before the demonstrations began, with a resurgent al-Qaida, a separatist movement in the south and a sporadic Shiite rebellion in the north vexing the government, which has little control outside major urban areas.