MANILA, Philippines — More than 300 families have been evacuated after massive amounts of ash billowed from the Mayon volcano over the weekend due to the collapse of lava deposits from its slopes, officials said Monday.

There was no explosive eruption from Mayon, which has been erupting mildly on and off since January, but huge deposits of lava on its southwestern slope suddenly cascaded down in a pyroclastic flow — an avalanche of hot rocks, ash and gas — before nightfall on Saturday, said Teresito Bacolcol, director of the Philippine Institute of Volcanology and Seismology.

No deaths or injuries were reported, but massive clouds of ash scattered over 87 villages in three towns, catching many by surprise and slowing down motorists due to poor visibility, officials said.

“The ashfall was just so thick and there was zero visibility even in our national road,” Mayor Caloy Baldo of Camalig town, which lies near the volcano’s foothills, said.

“Some villagers panicked but we advised them to calm down,” Baldo told The Associated Press.

Vegetable farms were damaged by the ashfall, which also killed four water buffaloes and a cow in Camalig, Baldo said, adding that a cleanup was underway in his town of 8,000 people in Albay province.

“It’s calm again now but the danger is always there,” Bacolcol said of Mayon’s condition Monday.

The 2,462-meter (8,077-foot) volcano is one of the Philippines’ top tourism draws because of its near-perfect cone shape. But it’s also the most active of the country’s 24 volcanoes.

Authorities raised the five-step alert around Mayon to level 3 in January after a series of mild eruptions that caused intermittent rockfalls, some as big as cars, from its peak crater along with deadly pyroclastic flows.

Alert 5 means an explosive and life-threatening eruption is underway with deadly volcanic lava and pyroclastic flows and heavy ashfall.