The day after 10 people were killed in street fighting between troops loyal to Saleh and soldiers and tribesmen who defected to the opposition, another large protest was planned for central Sanaa.
"There are one dead and six injured due to firing in the south of Change Square at dawn," said Dr Mohammed al-Qubati, the head of a field hospital set up in the protest camp.
A nine-month confrontation between Saleh and a fractured opposition of student protesters, tribal leaders and dissident army factions escalated in recent weeks after a three-month lull.
Saleh has thrice backed out of signing a Gulf-brokered transition plan and says he will only transfer power to "safe hands."
On Friday international efforts to end the violence moved to the United Nation Security Council, which approved a resolution condemning the crackdown on protesters and urging the veteran leader to sign the Gulf initiative, which would see him step down in return for immunity from prosecution.
The Arab League in a statement on Sunday welcomed the resolution, calling on Saleh to quickly sign the Gulf plan and allow its implementation to begin.
Tens of thousands of demonstrators set off on a protest march on Sunday from Change Square, the street intersection next to Sanaa University on the capital's ring-road where the opposition has set up camp.
In Saturday's clashes, five soldiers loyal to the opposition and five civilians were killed, witnesses and Sanaa residents said.
State news channels said five soldiers and three civilians had been killed, blaming the violence on non-government "militias."
Rocket-propelled grenades, mortars and automatic weapons were used in the al-Hasaba, Soufan and al-Nahda districts of northern Sanaa, where soldiers loyal to the opposition are based.