Ecuador shut schools in four towns near the Tunguarahua volcano as ash spewed more than two miles into the sky, damaging crops and endangering the health of nearby residents.
Authorities are urging people to cover their mouths and noses with masks and shut windows amid the furious venting of Tunguarahua that began on Monday.
The state Geophysical Institute said lava was flowing from the summit caldera - crater - down the flanks of the 16,480ft peak, 85 miles south east of the capital Quito.
The Education Ministry said classes in the nearby towns would be suspended.
Tunguarahua has been active since 1999. Its eruptions killed at least four people in 2006.