Santiago (Chile): An erupting Chilean volcano sent a towering cloud of ash across South America, forcing thousands people from their homes, grounding airline flights in southern Argentina and coating ski resorts with a gritty layer of dust instead of snow.

Booming explosions echoed across the Andes as toxic gases belched up from a three mile long fissure in the Puyehue-Cordon Caulle volcanic complex on Monday. A ridge between two craters just west of the Chilean-Argentine border began erupting on Saturday.

Winds blew a six-mile-high cloud of ash all the way to the Atlantic Ocean and even into southern Buenos Aires province, hundreds of miles to the northeast.

Authorities in Chile went house to house, trying to persuade stragglers near the volcano to leave because of an increasing danger of toxic gases and flash floods.

By Monday, about 4000 people had been evacuated from more than 22 communities.

They began fleeing as earthquakes on Saturday heralded the eruption and hundreds more fled on Tuesday to shelter farther away.

Some refused to leave, wanting to protect their homes and livestock.

Chile's verdant lakes region is a center for dairy farming, with more than 9,000 cows and sheep.

Deputy Interior Minister Rodrigo Ubilla said that about 50 families in the Rininahue area refused to abandon their homes.

"Everything is prepared with shelter and transportation for them to immediately leave the danger zone,” added Vicente Nunez, director of Chile's emergency preparedness office, urging them to leave. Just north of the complex of volcanoes, the city of Futrono and the communities of Lago Ranco and Entre Rios were particularly vulnerable to flash floods, “ He said.