People living near a chemical plant have been told to keep windows and doors shut after a white mist began emerging.
South Wales Police has advised the precautionary measure following the incident at Dow’s site in Barry, Vale of Glamorgan.
South Wales Fire and Rescue are in attendance with several crews at the scene and issued the same advice as police.
Residents in Dinas Powys, Sully and Penarth areas have been affected.
Silicone has been produced at the site, previously called Dow Corning, since 1952. About 630 people work there.
Dow said: “Dow Performance can confirm that the incident reported earlier has been brought under control.
“Dow emergency management team and South Wales Fire and Rescue Service have been stood down.
“The all clear klaxon has been sounded.”
The company is to investigate the matter to identify how to prevent it happening again.