- NEW: The violence comes after 21 people were killed in clashes between Yemen and al Qaeda
- The attack took place about 200 meters away from the presidential palace
- Last week, al-Qaeda called for the Yemeni people to rise up against the new president
- The soldiers were preparing for Tuesday's National Day of Unification events
Sanaa, Yemen (CNN) -- A suicide bomber dressed in a military uniform killed at least 47 soldiers Monday at the central security headquarters in Yemen, two intelligence officials said.
The soldiers were preparing for Tuesday's National Day of Unification ceremonies when they were attacked in the Yemeni capital of Sanaa. The blast wounded 36 other soldiers, the officials said.
The day celebrates the union of South Yemen and North Yemen on May 22, 1990, to form Yemen.
The attack took place about 200 meters (218 yards) away from the presidential palace.
"We heard a massive explosion. Minutes later, there were so many emergency vehicles, it seems as if hundreds were injured," said resident Ali al-Husseini, who was near the attack.
The defense ministry said the defense minister was at the scene of the attack but escaped unharmed. The country's chief of staff, Ahmed al-Ashwal, was also present.
No one immediately claimed responsibility for the attack.
Last week, al-Qaeda's leader called for the Yemeni people to rise up against the country's new president, portraying him as the stooge of the unpopular former president, Ali Abdullah Saleh, and the United States.
"So, Ali Abdallah Saleh is gone, and his successor Abed Rabbo Mansour Hadi has taken over," al Qaeda's chief commander Ayman al-Zawahiri said in a video posted on jihadist forums.
Saleh, who led Yemen for 30 years, relinquished power last year after an extended popular uprising in a transition agreement that was supported by the United States. But because Hadi was Saleh's vice president, al-Qaeda has exploited the connection to stir resentment against the new government.
Last year, Ansaar al-Sharia, an offshoot of al Qaeda, took over the majority of districts in the southern Abyan province, benefiting from the political turmoil in the country. Numerous military bases were evacuated, making it easier for the militants groups to grow in power and territory.
On Sunday, fierce clashes between government troops and al Qaeda fighters left 21 people dead, two local security officials said.
The officials said the violence erupted when hundreds of troops attempted to sweep through areas around the district of Jaar, the main stronghold for al Qaeda in Abyan province.
Al Qaeda fighters fought back, kicking off clashes that continued for nine hours, the officials said. Fourteen militants and seven troops were killed in the fighting, they said.
