Guatemala's Pacaya volcano belched columns of black ash on Friday, a day after a powerful eruption killed at least one person, forced hundreds of families to evacuate and shut the international airport.

The volcano, 25 miles south of Guatemala City, erupted on Thursday, raining thick ash and small rocks on the capital, coating the streets in a layer of gritty black sand.

A television journalist reporting from the slopes of the volcano died from head wounds when he was hit by falling lava rocks, according to a police spokesman.

President Alvaro Colom told a news conference that three children aged 7, 9 and 10 were missing after the eruption. Guatemala's Prensa Libre daily reported three dead, including the journalist, but police could not confirm the report.

All flights out of Guatemala City were cancelled due to the volcanic sand on the runways.

Pacaya, which is close to the colonial town of Antigua and farms where some of Guatemala's highest-quality coffee is grown, has been continuously active since the 1960s but had not showered rocks and ash since 1998.