MEDFORD, Oklahoma - Officials say Oklahoma Natural Gas crews have contained a propane leak that prompted a voluntary evacuation of a northern Oklahoma town.

ONEOK spokeswoman Megan Washbourne and Medford City Manager Dea Kretchmar said Sunday workers are still trying to cap the leak, but they were waiting on a part to finish the job. Washbourne said she couldn't identify what the part is.

The leak began Tuesday at a fuel-storage plant owned by ONEOK, which is ONG's parent company. Residents were evacuated out of concern the vapors could pose a fire risk if a pocket of propane ignited.

The Environmental Protection Agency said contractors planned to pump a brine and mud mixture into an underground well to stop the leak.

Kretchmar says residents who left their homes returned by Sunday.