UPDATE 9:05 p.m.:

A senior administration official tells CNN that Gaddafi's compound was targeted by coalition forces in a Sunday night airstrike because it has command center capabilities. However, the damage done to the building does not render it ineffective as a command center. There is still no indication that Gaddafi was in the compound when it was hit, and no evidence of casualties.

U.S. Secretary of Defense Robert Gates earlier Sunday urged coalition forces to stick to enforcing the U.N.'s no-fly zone resolution, and not target Gaddafi himself.

In a Pentagon press conference Sunday evening, Vice Admiral Bill Gortney said, "we are not going after Gaddafi," but also said that if the Libyan leader was "somewhere he shouldn't be," it's possible he could be wounded.

UPDATE 8:11 p.m.:

CNN's Nic Robertson, reporting from Gaddafi's compound in Tripoli, has a piece of a missile that appears to have hit the four-story building. The labeling on the debris is in English, and it could be a piece of a cruise missile of the type U.S. and British forces have been launching since Saturday afternoon.

Robertson said the debris he found was still warm, and nothing indicated it being planted or manipulated to falsely indicate a coalition attack.

UPDATE 7:28 p.m.:

CNN is reporting on-air that at least two cruise missiles struck the heavily fortified compound. One exploded upon contact, while the other missile exploded deeper inside the building. The roof of the building has collapsed, and there is no evidence that Gaddafi was inside.

AFP reports that the building hit was administrative and describes it as "flattened." The building is about 165 feet from the tent where Gaddafi typically greets visitors.

The blast occurred amidst heavy fire around 5 p.m. EST, around the same time as the Pentagon press conference where Vice Admiral Bill Gortney said, "We are not going after Gaddafi."

UPDATE 7:17 p.m.:

CNN's Nic Robertson is reporting on-air that what appears to be a missile has hit Gaddafi's compound and it is "very heavily damaged." It is not clear whose missile hit the building. No one has been reported injured or killed in this hit.

Robertson said that debris is strewn 150 yards from the compound.

EARLIER: Vice Admiral Bill Gortney, Director of the Joint Staff, delivered a brief update from the Pentagon on operations in Libya. He stressed that international coalition military force was being used to establish and enforce a no-fly zone over Libya, not to physically target Colonel Gaddafi or wrestle him from power.

"We are not going after Gaddafi," Gortney said, despite breaking reports of plumes of smoke being spotted near Gaddafi's residence in Tripoli.

"At this particular point I can guarantee that he's not on the targeting list.," Gortney said. However, he emphasized, coalition forces do not know of Gaddafi's whereabouts, so there is a chance he could be caught up in a strike.

No civilian casualties have been tallied, nor have coalition casualties. No coalition aircraft have been shot down. The UK, France, Canada, Italy, Belgium and Qatar are currently joining in coalition efforts in Libya, but Gortney said more countries would be announcing their participation as well.

Gortney was vague on details of how much enforcing the no-fly zone would cost, and who would shoulder what percentage of the financial burden, though one reporter theorized during the conference that it could cost from $100 million to $300 million. Gortney also dodged the question of who would lead the no-fly zone effort in the long run, for what he called a "more persistent presence," though he said that the mission is currently being led by the U.S.

He anticipated a "smooth transition to a coalition command structure in the next few days," but would not elaborate further.

Military action part of Operation Odyssey Dawn began Saturday afternoon, when French fighter jets fired on Libyan tanks. The U.S. also launched a total of 124 cruise missiles from ships yesterday, Gortney said.

The tomahawk missiles fired have been "very effective in significantly degrading the regime's ability to launch long-range air missiles."

Ten Air Force planes and 15 Marine planes, supported by French aircraft, also fired on Libyan ground forces 10 miles south of Benghazi, which Gortney said was "successful at halting the regime's ground movement in this region."

"Benghazi is not completely safe from attack, but it's certainly under less threat than yesterday."

Gortney was not optimistic about pro-Gaddafi Libyan cooperation.

"I question anything that Gaddafi calls for," he said. "He called for a cease-fire and then he moved his troops into Benghazi after the cease-fire."