(CNN) -- BP Chief Executive Officer Tony Hayward said Wednesday that it will be 24 hours before authorities will know whether the "top kill" effort to plug the runaway oil leak in the Gulf is working.
Speaking from a command center in Houston, Texas, nearly four hours after the effort began, Hayward said the operation was going according to plan, but cautioned against trying to reach any conclusions based on the video shots from the stricken well a mile below the surface.
"It's unlikely to give us any indication of what's really going on," he said. "Increases or decreases are not an indicator of success or failure at this time. We will be continuing for at least another 24 hours and it will be 24 hours before we will know whether or not this has been successful."