The A433 at Culkerton was closed both ways following a collision between two cars.
A woman was taken to Southmead hospital via air ambulance in a serious condition and one child has been taken to Bristol Children's Hospital.
A man in another car was taken to Swindon hospital.
The road had been closed for some time whilst a collision investigation takes place.
Anyone who witnessed the incident but hasn't yet spoken to police can call 101 quoting incident 149 of today's date (21 September).
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