GEORGETOWN, Guyana (AP) — A night-time fire raced through a school dormitory in Guyana early Monday, killing at least 20 students and injuring several others, authorities said.

“This is a horrific incident. It’s tragic. It’s painful,” President Irfaan Ali said, adding that his government was mobilising all resources to care for the children.

The government said several other students were being treated for injuries, and at least six of them were flown to the capital for treatment.

Ali said officials were contacting parents and mobilising psychologists to help deal with those affected by the fire.

“I cannot imagine the pain right now of the parents,” he said. “This is a major disaster.”

The fire began shortly after midnight at a school that serves mostly indigenous children aged 12 through 18, according to National Security Adviser Gerald Gouveia. He said it was too early to speculate what might have caused the fire, adding that heavy thunderstorms in the area posed a challenge to those responding by air.

“It was a battle for us,” he said. “The pilots were very brave, very determined.”

He added that the government and emergency responders “made a gigantic effort” to save as many people as possible.

Local newspaper Stabroek News reported that the fire broke out in a girls’ dormitory.

Opposition lawmaker Natasha Singh-Lewis called for an in-depth investigation.

“We need to understand how this most horrific and deadly incident occurred and take all necessary measures to prevent such a tragedy from happening again in the future,” she said.