ANCHORAGE, Alaska (AP) — The cause of a natural gas leak from a line that provides fuel for two Hilcorp Alaska offshore production platforms in Cook Inlet is being investigated. The Alaska Department of Environmental Conservation says a helicopter pilot spotted bubbles on the water’s surface and Hilcorp reported the leak to authorities on April 1. The report says Hilcorp shut down the platforms in response. It also says the leak was stopped on Saturday by activating block valves. A Hilcorp spokesperson says plans call for deploying divers to install a temporary clamp. The Anchorage Daily News reports a leak also occurred from the same pipe in 2017.