Mount Merapi, Indonesia ? Mount Merapi spewed a column of gas and sent clouds of hot ash tumbling down its slopes Thursday, causing 15,000 villagers to flee. Some jumped into rivers to escape the searing heat, and others sped off in trucks.

“I thought this is it,” said Udi Sutrisno, who grabbed a bag of clothes and abandoned his beloved farm with his wife and 10-year-old son as sirens wailed a warning. “We ran as fast as we could.”

No injuries or deaths were reported.

Indonesia’s most dangerous volcano has been venting steam and ash for weeks, but Thursday’s outburst at 9 a.m. was the largest yet. Dark gray clouds of hot ash and gas rolled 3 1/2 miles down the slope, said Sugiono, a government vulcanologist who like many Indonesians uses one name.

A series of powerful explosions were heard, some billowing columns of ash and gas a mile into the sky.

Some scientists say a May 27 earthquake that killed more than 5,700 people about 25 miles south of Merapi may have contributed to the volcano’s volatility in recent weeks.

An Indonesian golf course attendant walks across the course on her way to work as the Mount Merapi volcano erupts in Cangkringan village early today outside Yogyakarta, Indonesia. The volcano has been increasingly active since Monday, unleashing columns of hot gas and sending clouds of ash tumbling down its slopes.

The mountain’s lava dome has swelled, raising concerns that it could suddenly collapse, propelling scalding clouds of gas and rocks racing down its slopes into populated areas.

Yousana Siagian, a senior official at the government’s Vulcanology and Disaster Mitigation Center, said a 4.2-magnitude aftershock Thursday 17 miles south of the peak may have been a factor in the gas eruption.

Farmers carrying heaps of grass on their head ran down the mountain beneath a rain of ash, while others zipped off on motorcycles. Women clutching children jammed into trucks and cars, wiping away tears when they reached emergency shelters.

“I only had time to gather clothes for my children,” said Sartini, 24, one of hundreds of people who took refuge at a field dotted with Red Cross tents.

As she spoke, a red truck carrying 30 men, women and children lumbered into the makeshift camp in front of a government office, many smiling with relief.

Sutomo, a government official at the scene, said 3,500 people had fled Sleman district on Merapi’s southern side. Some 12,000 left their villages in Magelang district on the west.

Authorities had earlier urged residents to evacuate the danger zone near the volcano’s 9,700-foot-high peak, but thousands have stayed, saying they need to tend to livestock and crops on the fertile slopes.

One of those still on the mountain, Supriatun, said her small dairy farming community was untouched so far. “Of course, we’re worried, but as long as the hot clouds do not reach us, we won’t go,” she said during an interview by mobile phone.

Merapi’s last deadly eruption was in 1994, when it sent out a searing gas cloud that burned 60 people to death. About 1,300 people were killed when it erupted in 1930.