Cordon is in place while chemical is identified. Ambulance staff are treating nine people.
M6 closed in both directions between J3 A444 / B4113 (Nuneaton / Bedworth / Coventry) and J4 M42 / A446 (Coleshill), congestion on M6 to J2 M69 / A46 (Coventry) Northbound.
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The Black Country councillor is due to make an announcement today.
It seems people really do love the spread - and are stocking up on it - after the price row between Marmite supplier Unilever and Tesco.
Dry overnight with clear spells developing.