HARRISBURG (AP) - Democratic Gov. Tom Wolf's environmental protection secretary resigned Friday after Wolf's office began looking into an email the official sent to environmental advocacy groups from a private email address.

Wolf confirmed John Quigley's resignation in a brief interview with The Associated Press, but he did not explain the reasons behind it. The governor said Quigley did a fine job and that an interim secretary had been named.The resignation came hours after the governor's office disclosed its inquiry into the email.Democratic state Sen. John Yudichak saidthat "serious concerns" had been raised about Quigley's conduct.Quigley propelled the approval of new oil and gas industry regulations that overhaul waste is stored and considers its effect on public water resources, schools and playgrounds.Industry officials and Republican lawmakers opposed the regulations.David Masur, president of the environmental advocacy group PennEnvironment, said Quigley had been a strong advocate for the environment and public health in Harrisburg, "where they often don't have one."