A police department spokesperson said one of the 57 people injured appeared to be in critical condition.
"People were thrown into the air and onto the ground," passenger Elizabeth Banta told CNN. "There were definitely many people on the ground who were not moving."
More top news
Georgia Jones, 18, and Tommy Cowan, 20, were named locally as the pair who died after being taken ill at the Portsmouth event.
Targets for recycled and recyclable packaging should also be brought in to encourage firms to ‘harvest’ waste from consumers.
The store’s customer service, value for money and standard of stores were criticised by shoppers.