SANAA, Yemen -- Yemeni President Ali Abdullah Saleh was wounded when opposition tribesmen determined to topple him hammered his palace with rockets Friday in a major escalation of nearly two weeks of fighting with government forces. Seven guards were killed and eight senior figures from Saleh's regime were wounded.

The attack was a stunning hit on Saleh's leadership, striking a mosque in the palace compound where the president and top officials were praying. Saleh was taken to a Defense Ministry hospital and the extent of his injuries was not clear. After the attack, officials promised repeatedly that Saleh would appear to the public soon, but eight hours later state TV aired only an audio message from the president, speaking over an old still photo of him.

"If you are well, I am well," Saleh said in the brief message, addressing Yemenis. He spoke in a labored voice, his breathing at times heavy. He blamed the rocket attack on "this armed gang of outlaws," referring to the tribal fighters, and called on "all sons of the military around the country to confront" them.

One official said Saleh had slight neck injuries. The official spoke on condition of anonymity because he was not authorized to talk to the press. Deputy Information Minister Abdu al-Janadi spoke only of "scratches on his face."

"There is nothing affecting the president's health," al-Janadi said.

It was the first time that tribal fighters have directly targeted Saleh's palace in fighting that has rocked the capital since May 23. The violence comes as nearly four months of protests have failed to oust Yemen's leader of 33 years.

Sanaa residents have been hiding in basements as the two sides duke it out with artillery and gunbattles, shaking neighborhoods and sending palls of smoke over the city. Earlier Friday, intense government shelling flattened the homes of two tribal leaders and a military general who also joined the opposition.

The White House condemned the violence and called on all sides to stop fighting.

"Violence cannot resolve the issues that confront Yemen, and today's events cannot be a justification for a new round of fighting," said a statement from the White House press office.

President Barack Obama's Homeland Security and Counterterrorism adviser, John Brennan, discussed the crisis in Yemen with officials in Saudi Arabia and the United Arab Emirates during a three-day visit to the Gulf that ended Friday, vowing to work with Yemen's powerful neighbors to stop the violence.

Washington fears that the chaos will undermine the Yemen government's U.S.-backed campaign against Al Qaeda's branch in the country, which has attempted a number of attacks against the United States. Saleh, who is in his late 60s, has been a crucial U.S. ally in the anti-terror fight, but Washington is now trying to negotiate a stable exit for him.

Inspired by successful uprisings elsewhere, protesters have been trying since February to oust Saleh with a wave of demonstrations that has brought out hundreds of thousands daily in Sanaa and other cities, prompting often deadly crackdowns by government forces.

The crisis has escalated into a fight for power between two of Yemen's most powerful families: Saleh's and the al-Ahmar family, which leads Yemen's most powerful tribal confederation, called the Hashid.

Sheik Sadeq al-Ahmar, head of the Hashid, announced his backing for the protest movement in March, but it was only when Saleh's troops moved against al-Ahmar's residence in Sanaa last week that Hashid fighters erupted in retaliation, and the battles have escalated since.

On Friday, a volley of at least three rockets hit in and around Saleh's presidential compound. One struck a mosque in the compound where Saleh and senior officials were praying, a presidential statement read out on state TV said. In his audio message, Saleh said seven of his guards were killed, including the chief of his bodyguard contingent.

The blast wounded many in the top echelons of Saleh's leadership, including the prime minister, two deputy prime ministers, the heads of the two houses of parliament and the governor of Sanaa, as well as the mosque's preacher, said the official. The most serious injuries were to Sanaa's governor Nooman Dweid, and Deputy Prime Minister Rashad al-Alimi, who is also the president's top security adviser and who remained unconscious from his wounds, the official said, speaking on condition of anonymity because he was not authorized to talk to the press.

After the strike, state TV played national songs and showed footage of Saleh from his years in power, meeting world leaders and conducting visits to Yemeni cities. State media later went back and forth with reports that he would address the nation, and by late evening he had not appeared to the public.

More than 160 people have been killed in the Sanaa fighting since it began. Through the night, shelling and gunbattles raged in Hassaba, the northern neighborhood where Sadeq al-Ahmar's residence is located and where the battle has been concentrated. Over the course of the battle, tribesmen have overrun more than a dozen ministries and government buildings in and around Hassaba, artillery has demolished homes, and buildings have been set aflame.

Friday morning, troops expanded their shelling to the southern Hadda district of the capital, pounding the homes of two of al-Ahmar's brothers, Hameed and Himyar.

They also targeted the home of Gen. Ali Mohsen al-Ahmar, the commander of the powerful 1st Armored Division who has also joined the opposition but has so far stayed out of the battle. He is not related to Sadeq al-Ahmar. The houses were destroyed, witnesses said.

Saleh has agreed three times to sign onto a U.S.-backed, Gulf Arab-mediated agreement to leave power in 30 days, but each time he backed out of signing at the last minute.

The mediator of the deal, Abdul-Latif al-Zayani, appealed to Yemenis on Friday to end the fighting. "This is very regrettable and is of no benefit to anyone. The loser is the Yemeni people," al-Zayani, secretary-general of the Gulf Cooperation Council, which groups Gulf Arab nations, told Saudi-owned Al-Arabiya TV. He said the GCC is prepared to exert more effort to mend the differences between Yemenis, but he didn't elaborate.

Tens of thousands of demonstrators continue to mass daily in a central square of Sanaa, as well as in other cities.

Troops fired on protesters Friday in the city of Taiz, south of the capital, wounding two. A Defense Ministry statement said four soldiers were killed and 26 others injured in clashes there with gunmen it said were from the opposition and Islamist groups.

Despite the gunfire and shelling, protesters swarmed into a Sanaa main street for Friday prayers, and a series of coffins bearing victims of the past days' fighting were carried through the crowd. The cleric delivering the prayer sermon said Saleh was trying to turn the popular uprising into a personal conflict.

The president "wants to overturn this revolution and show the world that it is a conflict between al-Ahmar and Saleh," Imam Taha al-Mutawakil told the crowd.