Explosive eruptions have shaken two huge volcanoes in Central and South America, forcing thousands of people to flee their homes and disrupting air traffic as ash drifted over wide regions.

Guatemala's Pacaya volcano started spewing lava and rocks on Thursday, blanketing the country's capital with ash and forcing the closure of the international airport. President Alvaro Colom declared a "state of calamity".

Television reporter Anibal Archila was killed by a shower of burning rocks when he got too close to the volcano, about 15 miles south of Guatemala City, said David de Leon, a spokesman for the national disaster committee. The last images of Mr Archila broadcast by Channel 7 television show him standing in front of a lava river and burning trees, talking about the intense heat.

Mr De Leon said three children between the ages of seven and 12 were missing. At least 1,600 people from villages closest to the volcano were evacuated to shelters.

The volcano's eruption lost some intensity on Friday, although ash still rained heavily on nearby communities and constant explosions continued to shake the 8,373ft mountain, according to the Central American country's Geophysical Research and Services Unit. The unit reported an ash plume 3,000ft high which trailed more than 12 miles to the north-west.

In Guatemala City, bulldozers scraped the blackened streets while residents used shovels to clean their cars and roofs, carrying out large rubbish bags filled with ash into the streets. City officials pleaded with residents not to dump the ash into sewers. The blanket of ash was 3in thick in some southern parts of the city, and officials imposed limits on trucks and motorcycles to help speed up traffic.

La Aurora airport was expected to remain closed at least until Saturday as crews cleaned up, said Claudia Monge, a spokeswoman for Civil Aviation. Flights were being diverted to the Mundo Maya airport in northern Guatemala and Comalapa in El Salvador.

Meanwhile, strong explosions rocked Ecuador's Tungurahua volcano, prompting evacuations of hundreds of people from nearly villages. The National Geophysics Institute said hot volcanic material blasted down the slopes of the volcano, and ash plumes soared 6 miles above a crater which is already 16,479ft above sea level.

Officials said that within a few hours, winds already had blown the ash over the city of Guyaquil, 110 miles to the south-west. The eruption led aviation officials to halt flights out of Guayaquil and from Quito to Lima, Peru.

Institute researcher Sandro Vaca told Radio Sonorama that the eruption "seems to be growing rapidly". But there were no immediate reports of deaths.