BP officials released the first clear video of the primary leak at the Macondo Well site. In the video the flow is clearly evident - initially mixed somewhat with gas (most likely natural gas or possibly methane).
Something to think about... Estimates are that the flow emanating from break is blowing out at a whopping 15,000 to 25,000 psi.
To help frame that for you, a firehose typically blows between 100-300 psi, with a bursting max of 1200 psi.