The accident at Siam Paragon shopping mall appeared to have been caused by strong winds that caused the tent to collapse, said Lt. Gen. Sanit Mahathaworn, Bangkok's acting police chief.
"Strong wind caused the tent to fly up, about one metre. Then wooden signs attached to the back of the tent flew off and injured nearby people," he said.
Among the injured were at least 12 children, aged 6 to 9, who were among dozens of people at an event called "Pokemon Day Dance Party" to celebrate Thailand's Children's Day, Sanit and other officials said.
Siam Paragon issued a statement saying it "would like to regretfully apologise for the accident which injured a total of 16 people" on behalf of the event's organisers, which included other Thai companies. It said organisers sent all the injured to hospitals and by this evening only two remained hospitalised.
Sanit said that police would press criminal negligence charges against the owners of the company that installed the tent. They could face up to three years in prison and a 6,000 baht (USD 165) fine.