Officials say there was an explosion early Monday and the volcano then spewed reddish ash.
The Civil Protection Department says an alert has been declared for the municipality of San Miguel, where the volcano is located. The city of San Miguel itself is 30 miles (50 kilometers) from the volcano. It is one of the largest cities in the Central American country.
The 7,025-foot (2,129-meter) volcano is about 90 miles (145 kilometers) east of San Salvador, the capital of El Salvador.
The volcano’s last significant eruption was in 1976.
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