And for good measure

air vac·u·um (âr văk'yū-əm, -yūm, -yəm)
n., pl. -u·ums or -u·a (-yū-ə).

1. 1. Absence of matter caused by a bomb explosion.
   2. "not true".
   3. If your room is virtually airtight, and one electricity bulb bursts, it produces a big sound.
2. Bang created in buildings that are under high pressure.
3. A state of being sealed off from external or environmental influences; isolation.

Quote:
A hotel employee, Khurram Ahmed, told AFP: "It seems to be a bomb explosion. The bomb was apparently hidden in one of the flower pots near the entrance of the hotel. The blast was huge. It shook everyone in the hotel."

Information Minister Sheikh Rashid Ahmed said reports of a bomb were "not true".

"It was just an accident caused by short-circuiting and nothing else," he said.

Brigadier Javed Cheema of the interior ministry's national crisis management unit told AFP: "We haven't found any evidence that would suggest that it was an act of sabotage.

"The evidence indicates the blast was caused by short-circuiting. At the moment we rule out the possibility of any act of terrorism."

Brigadier Cheema said there could have been an air vacuum in the hotel.

"If your room is virtually airtight, even if one electricity bulb bursts, it produces a big sound," he said.

"These buildings are under high pressure so hence the bang was created."