BOGOTA, Colombia (CNN) -- A snow-capped volcano erupted and sparked landslides in southwest Colombia, killing at least six people -- four of them children, government officials and rescue workers said Sunday.
Three others are still missing.
The Nevado del Huila volcano erupted at 9:45 p.m. Thursday.
Gas and hot ash caused snow on the mountain peak to melt, sending mud, rocks and floodwater rushing down the River Paez and destroying at least 20 homes and washing out five bridges, the presidential office said in a statement.
Much of the sparsely populated region is a reservation for Nasa indigenous communities. All six killed were native Indians, according to the government. The youngest victim was 1 year old.
The worst-hit area was around the town of Belacazar, in southwest Cauca province.
By mid-afternoon Sunday, weather conditions were improving, but rescue workers said heavy rain since Thursday's eruption hampered relief work.
"Conditions are very good right now, but have been very changeable at night and first thing in the morning. That's meant rivers have flooded and made work very difficult," Col. Mervin Varon, director of disaster prevention for Colombian Civil Defense, told CNN.
Varon was speaking from the southwest town of La Plata, where a military air bridge has been set up to fly emergency supplies to the disaster zone.
Almost 300 people have been evacuated from homes around the volcano and along the route of the River Paez, government officials said. Relief aid, including water, cooking implements and baby diapers, is being distributed to 2,500 people.
The disaster struck as thousands of Colombian Indians, many from the eruption zone, marched into the capital to protest for land rights and a halt to free-market economic policies they say are condemning them to poverty.