HARRISBURG, Pa. (AP) — Pennsylvania regulators are fining a utility $500,000 for a 2011 natural gas explosion that killed five people in Allentown.

The Public Utility Commission on Thursday approved a settlement that also requires UGI Corp. to replace all its cast iron pipelines within 14 years and to enhance its testing and monitoring programs.

The cause of the February 2011 explosion was traced to a crack in a cast iron gas main.

Commission Chairman Robert Powelson and Vice Chairman John Coleman called the uitlity's safety record "downright alarming."

UGI, Pennsylvania's largest gas utility, UGI says it has accelerated the replacement of older gas pipelines. It says it also plans to "continue to work collaboratively" with state regulators to ensure gas is delivered safely.