Yemen's government and forces loyal to a dissident general declared a cease-fire Tuesday, hours after at least six people were killed during fighting in the capital and Yemen's second-largest city, Taiz.

Officials from both sides confirmed the agreement. Several previous truce accords have failed to hold.

Earlier in the day, medical workers reported two people killed and at least 40 wounded in Sana'a when security forces fired on anti-government protesters who were calling for President Ali Abdullah Saleh to step down. Government troops also clashed with dissident soldiers.

Meanwhile, at least four civilians were killed in the southern city of Taiz in crossfire between protest-supporting tribesmen and government troops.

President Saleh said Monday he welcomed a U.N. Security Council resolution urging him to sign a deal to leave office and said he is ready for talks to put a deal in motion.

A Gulf Cooperation Council proposal offers Mr. Saleh immunity from prosecution if he hands power to a deputy within 30 days. On at least three occasions, Mr. Saleh has refused to sign the plan, saying he first wants international guarantees about a timetable for its implementation.

Also Tuesday, Yemeni security officials say a military plane crashed while landing at an air base in the country's south, killing at least four people.

Officials said the crash in Lahej province was likely caused by a technical problem.

Reports say there were 15 people on board the plane, eight Syrians and seven Yemenis.

Yemeni troops have been battling al-Qaida-linked militants in the south for months as political unrest also grips the country.