On the edge of this town near Popocatepetl volcano, away from the clamor of traffic, there was an occasional low rumble on Monday, like an idling engine.

A cloud of superfine ash descended, reducing visibility slightly and coming to rest on the windshields of vehicles. For more than a week, the 17,797-foot mountain just 45 miles southeast of Mexico City and affectionately known as “El Popo” has been erupting rapidly, spewing gas, ash and incandescent plumes into the air. Big piles of rock are spewing out.

The activity led the Mexican government to raise the alert level and close schools in dozens of municipalities in three states. On Monday, local, state and federal officials conducted drills for the possibility of evacuation.

“You hear it more at night,” said Violeta Fuentes, 39, who lives with her husband and two children, ages 9 and 12, on the outskirts of Santiago Xalitzintla. That too when they can see the glow from the crater. “Last night, several times it would go out for a moment and light up again.”

Fuentes said she was a little nervous about it “because you can see (the volcano) doesn’t want to recover anymore.” The family was worried about the impact of the ash fall on their crops. His father-in-law’s grain across the road was already wrapped in it.

However, alert and preparedness is old hat for residents here.

Job Amalko, a driver, said it was normal. “It does not scare us. We are spectators of what nature gives us,” he said proudly.

But concern was growing among some.

“It’s worrying because of the kids, because you don’t know if it’s going to be a big explosion or a small one,” said Claudia de la Cruz, 27, a mother of two children aged 3 and 5.

Her husband climbs the sides of the volcano every day to collect firewood to make charcoal. “He says there it looks like the peaks are falling down and it’s shaking, but he’s brave for us,” she said.

De la Cruz recalls as a girl the first time she saw the mountain glow and how the inhabitants at the time had little knowledge of it. He is confident that now with a cellphone he will know in real time what is happening.

Still, the real warning residents would hear – as it has been his entire life – would be the immediate tolling of the town’s church bells. On Monday they went out as part of the drill.

There were no signs of panic on Monday, but people were worried about the prospect of evacuees leaving homes and animals unattended. Officials have warned people to stay out of a 7.5-mile radius around the peak.

Florencio de Ollart, 69, and Plácida de Aquino, 72, recalled having to evacuate their home in the city center twice years ago. On those occasions, “you could see (the volcano) lit up, throwing rocks,” Olarte said.

One of their children already wants them to come to Mexico City, but the couple don’t want to leave before the authorities tell them they have to go because of their turkey, pig and donkey. “We have animals and we cannot abandon them,” Aquino said.

Aquino said, “There’s a lot of smoke now and it rumbles and rumbles, the curtains move.” But nothing more for the time being.

The volcano’s activity temporarily halted flights at two of the capital’s airports over the weekend.

On Monday, the ash plume stretched hundreds of miles to the east, stretching over the Bay of Campeche, the US National Oceanic and Atmospheric Administration reported.

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On Sunday, national civil protection coordinator Laura Velazquez said at a news conference that the stoplight-style warning system for the volcano was at yellow but had risen to stage 3. Still, she added, “there is no risk to the population at this time.”

In this phase, large domes develop and explode in increasing intensity, launching incandescent rock into the air and pyroclastic flows down its sides.

Velazquez said only three of the volcano’s 565 eruptions since September were major, and the current activity was not the biggest this century. On Monday, he inspected the drill in Santiago Xalitzintla.

“We don’t know what’s going to happen,” she said on Monday. “We are prepared for any scenario.”

The Defense Department said it was ready to activate 6,500 troops if necessary. Shelters were being prepared.

Some 25 million people live within a 60-mile radius, most of which are in Mexico City’s metropolitan area.

Popocatepetl came to life in 1994 after a decade-long dormancy and experienced more activity from 2000 to 2003 and 2012 to 2016.