Wildfire kills 4 firefighters in Indonesia's Mount Bromo national park

At least four people have died and two others suffered severe burns while battling wildfires in a national park on Indonesia's main island, officials said on Friday.

They were trapped by thick smoke and fast-spreading flames in the Bromo Tengger Semeru National Park in East Java, a Forestry Ministry statement said, as the country's worst wildfires in a decade swept through the area.

The southeast Asian country has been battling a months-long crisis of blazes and toxic smoke, forcing schools to shut down and causing a surge in respiratory complaints in the region.

The victims were part of a 12-member firefighting team consisting of national park personnel, members of the community fire brigade, and local volunteers, said East Java police spokesperson Jules Abraham Abast.

"This incident serves as a reminder that forest and land fire extinguishing is a high-risk operation," the ministry statement said, adding there had been a jump in hotspots detected by satellites as areas of unusually high temperatures. Not all hotspots necessarily translate into individual fires.

By Thursday evening, the number of hotspots in Indonesia stood at 799, up from 372 a day earlier. The forest and land fires have worsened this year as weather phenomenon El Nino prolonged the dry season.

Toxic haze spreads across southeast Asia

The smoke from Indonesia's wildfires are causing a health crisis in neighboring southeast Asian countries such as Singapore, Malaysia and the Philippines.

Malaysia on Friday ordered hundreds of schools to close down due to deteriorating air quality.

Singapore, meanwhile, topped IQAir's live ranking of the world's most polluted major cities, with Kuala Lampur second and Jakarta sixth.

Malaysian Foreign Minister Mohamad Hasan rejected calls from some lawmakers to seek compensation from Indonesia, saying the crisis should be addressed through diplomatic engagement and established mechanisms.

He said Malaysia was coordinating assistance for Indonesia and would push for stronger regional cooperation on haze management.

Singapore probing companies linked to fires

Singapore also called for closer cooperation. Prime Minister Lawrence Wong said authorities were investigating companies allegedly linked to Indonesian forest and land fires that have worsened the haze.

"Where warranted, we will take action under Singapore's Transboundary Haze Pollution Act, and also explore joint action with other countries," he said.

Singapore enacted the Transboundary Haze Pollution Act in 2014 after a bout of severe pollution.

The law allows authorities to target companies whose activities overseas cause or contribute to unhealthy haze levels in Singapore. That said, legal experts cautioned that pursuing companies under the law will be challenging.