SANAA, Yemen — Yemen's defense minister escaped a car bomb on his motorcade on Tuesday that killed at least 12 other people, a day after the U.S.-backed government said it had dealt a crushing blow to al-Qaida by killing its regional branch's second in command.

Witnesses said the blast happened as Major General Muhammad Nasir Ahmad's motorcade left the prime minister's office in Sanaa after a Cabinet meeting. Interior Minister Abdul Qader Qahtan told state television that seven security guards and five civilians were killed and 12 other people were wounded.

Aides said the minister was unhurt and had told Prime Minister Mohammed Basindwa he was safe.

"A booby-trapped car waited for the motorcade of the minister near the government offices and as soon as it moved, it exploded," a security source told Reuters. "A security car was totally destroyed and all its occupants were killed, but the minister survived because his car is armored."

Officials say Tuesday's attack was the fourth assassination attempt against the defense minister since a new government was formed last December, after a power transfer deal under which long-ruling President Ali Abdullah Saleh stepped down.

No one immediately claimed responsibility for the attack, which followed the government's announcement of the killing of Said al-Shehri, deputy head of the Yemen-based branch of al-Qaida, which wants to topple the governments of Yemen, Saudi Arabia, and other states in the region.

Al-Qaida blames the defense minister for leading a campaign that drove it from strongholds in southern Yemen, an area that Washington considers one of the main battlefields in its global campaign against Islamist militants.

Yemen's government said it had killed Shehri in a military operation, but Yemeni security sources said he was one of six suspected militants killed last Wednesday in a strike by U.S. drone.

The United States does not comment on its use of unmanned aircraft against militants, which has enraged the public in Yemen because of civilian deaths. A separate apparent drone strike last week hit the wrong target and killed ten civilians.

"Shehri's death is a painful blow to al-Qaida after the grievous losses it suffered in Abyan," state-owned daily al-Thawra said in a front page headline, referring to a province where the army had forced Islamist militants from this year.

Shehri was wanted by Yemeni, Saudi, and U.S. authorities over his role in Al-Qaida in the Arabian Peninsula (AQAP).

A former inmate of the U.S. prison camp at Guantanamo Bay, Shehri was freed to Saudi Arabia by the George W. Bush administration in 2007. After a time in a Saudi militant rehabilitation program he escaped to Yemen and is suspected of a role in a 2008 attack on the U.S. Embassy.

Last year Yemen claimed it had killed him, only for it to emerge Shehri was still at large.

ANGER OVER CIVILIAN DEATHS

Analyst Nasser Arrabyee said the Yemeni government wanted to claim a success to win the public over to the U.S.-led campaign.

"People are angry because of the mistakes that were made when people were killed," he said. "But most people know that al-Qaida should be defeated and is dangerous for the country."

Leaked U.S. diplomatic cables showed Saleh agreed in 2009 to a covert U.S. war on Islamist militants and would claim Yemeni responsibility for attacks when necessary.

Saleh was eventually swept from power under a negotiated deal after a popular uprising that became one of the most drawn out and violent of the "Arab Spring" revolts, during which al-Qaida seized towns and villages in the south.

His successor, Abd-Rabbu Mansour Hadi, has pledged to reunify the country and press on with the fight against al-Qaida. Many Yemenis say the U.S. focus on militants is diverting attention and resources away from other pressing issues such as unemployment, corruption, water depletion, and economic revival.

"The government is certainly keen to show they are active and successful in the fight against al-Qaida and at the same time to tell its own people there is no active and open U.S. military action," said Ghanem Nuseibeh, senior analyst with Cornerstone Global. "The authorities seem to have decided that claiming responsibility is less risky than saying the Americans did it."

Thousands of Yemenis marched through Sanaa on Tuesday to demand Saleh be tried over corruption and the deaths of protesters, denouncing the U.S.- and Saudi-backed power transfer deal that gave him immunity from prosecution for standing down.

"The people want the fall of his immunity," they chanted, in a play on the Arab uprising slogan "the people want the fall of the regime". Security forces closed off streets around Saleh's house to prevent the marchers getting near.

SAUDI ARABIA HAPPY

Security experts close to Saudi Arabia's intelligence establishment said Shehri's death would weaken al-Qaida's ability to stage attacks on Saudi soil.

Shehri was seen as leading the Saudi faction within AQAP, a movement sworn to bring down the ruling Al Saud family. He was on a list of 85 wanted militants issued in 2009.

"His preoccupation was Saudi Arabia and re-establishing al-Qaida there. He wasn't a symbol like Osama bin Laden, but an operational leader who recruited, planned, and was heavily involved day to day," said Mustafa Alani, head of the Gulf Research Center in Jeddah.

"Killing this sort of leader is going to undermine the Saudi faction within al-Qaida in Yemen and the morale of the Saudis there," he said. "Mostly the ones killed before have been Yemenis. The Saudis are the big names in AQAP but they had remained safe."

Al-Qaida launched a campaign of suicide attacks targeting government installations and foreign residents in Saudi Arabia in 2003. The government has brought it to an end by 2006 and the Yemeni and Saudi wings of the global network joined forces using Yemen as their base in 2007.

Alani said around a fifth of AQAP was made up of Saudis, but that they constituted much of the movement's leadership while Yemenis provided the foot soldiers.