A major investigation was under way today following a serious chemical spill at a sewage plant in Southend.

Six Anglian Water employees were rushed to hospital after two substances mixed to form a potentially lethal chlorine gas.

People living next to the works in Stock Road, Southend, were warned to stay indoors and shut all windows and doors.

Residents in Shoebury were put on alert over fears that a cloud of gas may have been heading in their direction.

Football matches on nearby sports pitches were also postponed as a precautionary measure.

Fire crews were called in at around 8.30am on Saturday after workers raised the alarm.

Kitted out in breathing apparatus, they diluted the chemical mix and made the area safe.

Essex Police spokesman Heather Watts stressed the emergency measures were precautionary, but necessary.

She said: "This was quite a low-risk incident.

"There was a strong wind and we believe if any gases were released into the atmosphere then they would have dispersed very quickly.

"We would like to thank all those homeowners who reacted well to this precaution."

Normal programmes on Essex's radio stations were interrupted to give out warnings to people affected.

A spokesman for Anglian Water said experts were today probing the cause of the incident.

He said: "We do all we can to ensure the safety of the public in our work. We are attempting to find out what happened at the Anglian Water works and we will make sure it never happens again."

The all-clear was sounded at around 1pm when firefighters had finished mopping up.

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