Participants at the UN COP30 climate talks were evacuated after a fire broke out at the venue in Belem, Brazil.
BBC journalists saw flames and smoke in the pavilion area before being forced outside where fire trucks rushed past.
The UN said the fire was extinguished within six minutes and 13 people were treated for smoke inhalation. It is not yet known what caused the fire.
The talks were in the final hours of attempts to agree on next steps to tackle climate change, but the fire derailed the talks and the talks remain closed.
“It was climbing the walls and ceiling. People were screaming,” Dr Harshita Umesh, who was speaking near where the fire broke out, told BBC News.
“Then I ran, I think I tripped and fell.”
Dr. Umesh, a physician, said she was told by emergency personnel that emergency workers had inhaled “toxic fumes” and were given oxygen masks at the scene.
Emergency medical technician Kimberly Humphrey, who is currently helping patients at COP Medical Centre, told the BBC that the injuries were “mainly smoke inhalers and someone with lung damage from the smoke”.
“People are very traumatized and shocked,” she added.
“There is huge panic here, people are running away, it's a very dramatic moment… UN guards are telling us to leave,” BBC climate editor Justin Rowlatt said shortly after the fire broke out.
“You can see huge plumes of smoke rising into the air through a hole burned into the top of the convention center,” he said.
BBC journalists saw two ambulances driving towards the entrance more than 90 minutes after the fire started.
A Brazilian security officer who placed a chain on the establishment's gate told the BBC the premises needed to be evacuated and locked.
After the fire broke out, orange flames burned a hole in the protective coating covering the site, which is located on a former airfield. One video shows a man spraying a fire extinguisher on a fire before running away.
One witness told the BBC he believed the fire was caused by electrical wiring.
The woman was taken away in a wheelchair, but it is unclear if this was related to the fire.
Hundreds of people were left sitting on the floor or on plastic chairs outside in high temperatures and humidity.
The fire is likely to delay the conclusion of a deal in negotiations.
A number of delegations were forced to take shelter outside under the roof of a gas station, a member of the British delegation told the BBC. He said the fire stopped negotiations.
The UN, which hosts the COP climate meetings, said a fire brigade was checking the venue to assess safety and that the summit had temporarily been taken over by Brazilian authorities.
Thousands of people attend UN climate talks, including members of delegations from around the world.
Some 200 countries are trying to agree on how to make progress on climate change.
