ENSENADA, CHILE (TIP): Twin blasts from the Calbuco volcano in southern Chile sent vast clouds of ash into the sky, covering this small town with thick soot and raising concerns on Thursday that the dust could contaminate water, cause respiratory illnesses and ground more flights.

Ensenada, in the foothills of the volcano, looked like a ghost town but for an occasional horse or dog roaming its only street. Most of the 1,500 residents had evacuated after the initial eruption on Wednesday, with only about 30 people refusing to leave out of worry for their homes and animals.

Daniel Patricio Gonzalez left with his wife, 7-year-old son and 4-year-old twins, but he returned to town Thursday night to assess the damage. The roof at the restaurant he manages had caved in from the weight of the mounting ash.

“This hurts a bit, but there’s nothing to do against nature. The important thing is that my family is fine,” Gonzalez said.

The volcano erupted Wednesday afternoon for the first time in more than four decades, spewing out a plume of ash more than 6 miles (10 kilometers) high. Emergency officials were taken by surprise and had only a few minutes to issue an alert.

Calbuco had another spectacular outburst early Thursday with lightning crackling through a dark sky turned reddish orange by the explosion.

As the ash cloud spread Wednesday, “people went into a state of panic,” said Miguel Silva Diaz, an engineer who lives in Puerto Montt, a city about 14 miles (22 kilometers) from the volcano. “Then, at around 1am, I heard a loud noise, as if somebody had detonated an atomic bomb.”

Winds blew ash in a widening arc across to Argentina. No injuries were reported and the only person reported missing since the eruption was located on Thursday.

Authorities evacuated 4,000 people as gas and ash continued to spew, and they closed access to the area around the volcano, which lies near the cities of Puerto Varas and Puerto Montt, some 620 miles (1,000 kilometers) south of Santiago.

“I was shocked. I had just arrived home when I looked through the window and saw the column of smoke rising up. We called our families, posted photos,” said Daniel Palma, a psychologist who lives in Puerto Varas.

“We woke up today with a blanket of fog and it hasn’t cleared. We have a layer of smoke above us,” Palma said, adding that many were concerned about the possible effects of the ash on their health.

The Chilean national geology and mining service warned that people should prepare for a third and “even more aggressive eruption.”

President Michelle Bachelet, who visited the area Thursday, declared a state of emergency.

“We don’t have any problems with supplies, water or sewage up to now. That’s not the problem,” she said. “Our problem is a respiratory one, from inhaling all of this ash, and the fact that this ash could generate some sort of environmental contamination.”

The short-term dangers related to the ash include eye and skin infections as well as water contamination, said Bernardo Martorell, a physician and the head of the sanitary planning division at Chile’s health ministry.

“That’s why the people in the area need to evacuate,” Martorell said.

The ash continued to fall Thursday in Puerto Montt and other nearby cities. Patricio Vera, director of a local radio station, said that after the initial eruption, hundreds of people rushed to buy gasoline, forcing stations to ration sales, while supermarkets closed early to avoid the risk of looting.

LATAM and other airline companies cancelled flights to and from Puerto Montt because airborne ash can severely damage jet engines.

The 6,500 foot (2,000-meter) Calbuco last erupted in 1972 and is considered one of the top three most potentially dangerous among Chile’s 90 active volcanos.

By Thursday afternoon, ash had made its way to Villa La Angostura, Argentina, a small town about 56 miles (90 kilometers) northeast of Calbuco. Cars and streets were coated with a thin layer of ash, but people were otherwise going about their business.

“We are praying that the volcanic activity will be as short as possible,” said mayor Roberto Cacault.