A low-level leak of mustard agent has been detected in the same storage building at Aberdeen Proving Ground that reported similar discharges in June, the Army said yesterday.

The Army, which operates the Harford County proving ground, said an alarm sounded at 12:45 p.m. indicating a low-level presence of mustard agent vapor inside the sealed storage structure that houses steel containers of the deadly chemical. No vapor was detected outside the building and at no time was there any danger to facility workers, the community or the environment, the Army said in a prepared statement.