MEXICO CITY (AP) — An explosion at the crater of Mexico's Popocatepetl volcano hurled incandescent rock about a mile (1.6 kilometers) down its slopes Thursday.

The blast early also sent a column of ash 2 miles (3 kilometers) into the sky near the nation's capital.

Mexico's civil defense office said ash fell on four towns near the crater following the outburst.

The 17,797-foot (5,426-meter) volcano has been particularly active in recent months, several times spewing out sprays of hot rock and towering clouds of ash

Some 25 million people live within about 60 miles (100 kilometers) of the mountain's crater.