Following a recent volcanic eruption in Indonesia’s most populated island of Java, the death toll has risen to 13 while 7 people are reported missing according to officials on Sunday.

Mount Semeru in Lumajang district in East Java province spewed thick columns of ash more than 12,000 meters (40,000 feet) into the sky, and searing gas and lava flowed down its slopes after a sudden eruption Saturday triggered by heavy rains. Several villages were blanketed with falling ash.

This was followed by a thunderstorm and days of rain which caused severe erosion which finally collapsed the lava dome atop the 3,676-meter (12,060 foot tall) Semeru which triggered a severe eruption – says Eko Budi Lelono who is the head of the geological survey center.

He also added that the flows of searing gas and lava further traveled up to 800 meters (2,624 feet) to a nearby river twice on Saturday.

People were however advised to stay 5 kilometers (3.1 miles) from the crater’s mouth.

“Thick columns of ash have turned several villages to darkness,” said Lumajang district head Thoriqul Haq.

Because of that, people had to be moved to temporal shelters while others were left in safe areas even though power blackout affected the evacuation.

The debris and lava mixed with rainfall formed thick mud that destroyed the main bridge connecting Lumajang and the neighboring district of Malang, as well as a smaller bridge, Haq said.

Despite an increase in activity since Wednesday, Semeru’s alert status had remained at the third-highest of four levels since it began erupting last year, and Indonesia’s Volcanology Center for Geological Hazard Mitigation did not raise it this week, Lelono said.

A National Disaster Mitigation Agency spokesperson Abdul Muhari announced that at least 13 villagers had died from severe burns while 57 others were hospitalized including 16 in critical condition with severe burn injuries.

He also added that a rescue team is still on the lookout for seven missing residents and sand miners along a river in Curah Kobokan village where they were reported missing.

Entire houses in the village were damaged by volcanic debris and more than 900 people fled to temporary government shelters, Muhari said.

The head of Semeru’s monitoring post, Liswanto added that his office had informed the community and miners that hot ash could tumble down from Semeru’s crater at any time after sensors picked up increased activity in the past week.

But some residents who fled to a government shelter near Lumajang district’s head office said authorities did not convey any information to them about the volcano’s activities.

“Suddenly everything went dark, the bright afternoon turned into night. A rumbling sound and heat forced us to run to the mosque,” said Fatmah, a resident who fled to the shelter from Curah Kobokan, about 5 kilometers (3 miles) from the crater. “It was a far stronger eruption than in January.”

Adita Irawati who was Transportation Ministry’s spokesperson said her office had issued a notice on Saturday for all airlines to avoid routes near the volcano.

She further added that airlines are still running on schedule and that authorities will continue to monitor the situation.

The Darwin Volcanic Ash Advisory Centre said the spread of volcanic ash from Mount Semeru was detected to the southwest moving at a speed of 50 knots.

Television reports showed people screaming and running under a huge ash cloud, their faces wet from rain mixed with volcanic dust. The last time Semeru erupted, in January, there were no casualties.

Indonesia is among the world’s most populous countries with over 270 million people and the country is prone to natural situations such as earthquakes and volcanic activity due to its location along the Pacific “Ring of Fire,” a horseshoe-shaped series of fault lines.

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