NEW ORLEANS (AP) — BP has started testing a cap designed to stop the flow of oil into the Gulf of Mexico for the first time in almost three months.

Kent Wells, a senior vice president in the company, said at a Wednesday evening news briefing that the valve on the top portion of the cap was shut, meaning the oil had stopped pouring out from there. It was working to shut off the other two valves to completley close the oil in. Wells says the process will take hours.

The cap is a stopgap measure designed to keep the oil in the well or funnel it to ships until the relief well is done