Emergency management officials in Washington County have begun permitting residents to return to about 30 homes in Monongahela after containing a chlorine leak at a business tonight.

Metal Management, at 770 E. Railroad St., reported that a 150-pound cylinder of chlorine leaked just after 5 p.m., Washington County dispatchers said.

Police, fire and emergency personnel joined a hazardous materials team to contain the leak, dispatchers said. Residents of the neighborhood initially were ordered to leave, but were permitted to go home at 7:30 p.m.

The cause of the leak remained unclear.