DAMASCUS (AP) -- Two massive explosions rocked the heart of the Syrian capital on Wednesday, striking near the army and air force command headquarters and sending huge columns of thick black smoke over Damascus.

The bombings were the latest to hit the city as the uprising against President Bashar Assad’s regime intensifies, highlighting the increasingly deep reach of the rebels determined to topple him.

Syria’s state-run news agency SANA said a fire broke out in the area after the twin blasts, which struck just before 7 a.m. near the landmark Omayyad square. The explosions shattered the windows of nearby buildings, including the entire facade of the Dama Rose hotel which overlooks the area, and were heard several kilometers away.

Information Minister Omran Zoubi said the blasts were caused by two “large, highly explosive” improvised devices, one of which may have been placed “on the inner side of the fence” around the grounds of the army command building. He said the damage inflicted was material and there were no casualties.

“I can confirm that all our comrades in the military command and defense ministry are fine,” he told Syrian TV, which is located near the site of the explosion, in a telephone call.

“Everything is normal,” he said. “There was a terrorist act, perhaps near a significant location, yes, this is true, but they failed as usual to achieve their goals.”

Black smoke rose high into the air and ambulances were rushed to the site as police sealed off the area to traffic and journalists. Witnesses said the explosions were followed by heavy gunfire, suggesting security forces clashed with gunmen in the high security area.

Syria’s unrest began in March 2011 when protests calling for political change met a violent government crackdown. Many in the opposition have since taken up arms as the conflict morphed into a civil war that activists say has killed nearly 30,000 people. Over the past few months, the rebels have increasingly targeted security sites and symbols of regime power in a bid to turn the tide in the fighting.

On July 18, rebels penetrated the heart of Syria’s power elite, detonating a bomb inside a high-level crisis meeting in Damascus that killed three top regime officials, including Assad’s brother-in-law and the defense minister. Other large blasts have targeted the headquarters of security agencies in the capital, killing scores of people this year.

And on Tuesday, several bombs went off inside a Damascus school that activists said was being used by regime forces as a security headquarters. Several people were wounded.

Syria’s conflict was the focus of attention as world leaders gathered at the U.N. General Assembly‘s annual meeting in New York this week.

U.N. Secretary-General Ban Ki-moon demanded international action to stop the war in Syria, telling a somber gathering of world leaders Tuesday that the 18-month conflict had become “a regional calamity with global ramifications.”

Ban, declaring that the situation in Syria is getting worse every day, called the conflict a serious and growing threat to international peace and security that requires attention from the deeply divided U.N. Security Council.

That appears highly unlikely, however, at least in the near future.

Russia and China have vetoed three Western-backed resolutions aimed at pressuring Assad to end the violence and enter negotiations on a political transition, leaving the U.N.’s most powerful body paralyzed in what some diplomats say is the worst crisis since the U.S.-Soviet standoff during the Cold War.

In sharp contrast to the U.N. chief, President Barack Obama pledged U.S. support for Syrians trying to oust Assad -- “a dictator who massacres his own people.”