OKLAHOMA CITY — A drilling rig explosion that killed five workers earlier this year may have happened after the crew misread signs of a high-pressure "kick" that allowed natural gas to escape from the well and a crucial piece of safety equipment failed to stop the blowout, federal investigators said.

Nearly a year after Hurricane Harvey struck the Texas coastline, environmentalists say state regulators should do more monitoring and oversight to help prevent the kind of unchecked pollution that occurred during the storm.

A trade group representing most of the U.S.'s long-distance natural gas haulers pledged to reduce the amount of methane released from pipelines and storage facilities, although it doesn't go as far as other voluntary efforts to address the potent greenhouse gas.

As the shale industry enters its second decade, its influence on politics remains one of its biggest legacies.

Colorado voters may get a chance to vote in November on a proposal that would severely curtail oil and gas development in the state.