Rocks spewing from a volcano overlooking the Guatemalan capital killed a television reporter and crushed roofs in villages near the peak, authorities said Friday while also reporting three children were missing.

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

"We thought we wouldn't survive. Our houses crumbled and we've lost everything," said Brenda Castaneda, who said she and her family hid under beds and tables as marble-sized rocks thundered down on her home in the village of Calderas. The family was waiting for rescue teams to take them to a shelter at a nearby school.

Television reporter Anibal Archila was hit by a shower of burning rocks when he got too close to the volcano, about 25 kilometres south of Guatemala City, said David de Leon, a spokesman for the national disaster committee.

The last images of Archila broadcast by Channel 7 television show him standing in front of a lava river and burning trees, talking about the intense heat.

De Leon said the three missing children are between seven and 12 years old.

At least 1,600 people from villages closest to the volcano have been evacuated to shelters.

Falling ash

The volcano's eruption lost some intensity Friday, though ash still rained heavily on nearby communities and constant explosions continued to shake the 2,552-metre mountain, according to the Central American country's Geophysical Research and Services Unit.

The unit reported an ash plume 1,000 metres high that trailed more than 20 kilometres to the northwest.

Ash no longer fell over Guatemala City, where bulldozers scraped up blackened streets. Residents used shovels to clean their cars and roofs, carrying out large garbage bags filled with ash into the streets. City officials pleaded with residents not to dump the ash into sewers.

The blanket of ash was 7.5 centimetres thick in some southern parts of the city, and officials imposed limits on trucks and motorcycles to help speed up traffic.

The government urged residents not to leave their homes unless there was an urgent need.

Airport closed

La Aurora airport will be closed at least until Saturday as crews clean 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.

While the Guatemala eruption shut down local flights, it was not expected to affect airports in neighbouring countries like Iceland's Eyjafjallajokul volcano did.

The ash erupting from Pacaya is thick and falls quickly to the ground, unlike the lighter ash that spewed from the volcano in Iceland and swept over much of Europe, disrupting global air travel, said Gustavo Chigna, a volcano expert with Guatemala's institute of seismology and volcanos.

The most active of Guatemala's 32 volcanos, Pacaya has been intermittently erupting since 1966, and tourists frequently visit areas near three lava flows formed in eruptions between 1989 and 1991.

In 1998, the volcano twice spewed plumes of ash, forcing evacuations and shutting down the airport in Guatemala City.