At least 200 people were said to be missing Friday by firefighters after a dam burst at a Brazilian mine and caused severe flooding in the southeastern state of Minas Gerais.

Dramatic aerial footage from CNN affiliate Record TV showed the city of Brumadinho covered in mud. Homes appeared to have been destroyed, and helicopter rescues led by firefighters showed people covered in mud being airlifted out of the area.

The Feijao mine is managed by Brazilian mining giant Vale, which said it suffered a “breach,” causing mining debris to spill into the mine’s administrative area where employees were working.

Fabio Schvartsman, Vale president, said he felt “great regret” about the incident.

“I ask for forgiveness from all those affected and all of Brazilian society,” Schvartsman said in a video distributed by the mining company and carried on the local Globo news network.

Vale’s press department said a triage area had been set up in a nearby football field for victims to receive medical treatment. The statement said more than 50 firefighters and six aircraft had been deployed there.

Schvartsman said the company put an “immense effort” into improving its dams, especially after a similar mining disaster in 2015 in the city of Mariana.

“Unfortunately, the dam break (today) happened. This is inexcusable,” Schvartsman said, adding the company will “do all possible” to aid victims.

“What just happened just now is beyond anything that I could imagine,” he said.

Brazilian President Jair Bolsonaro posted a series of tweets to his official Twitter account, saying the government’s “main concern at this moment is to tend to the potential victims of this horrific tragedy.”

Bolsonaro said he had deployed the ministers of the environment and mining and energy and national defense secretary to the area and that “all possible measures” are now in place.