Scientists said the volcano had spat rocks as far as 1.5km from its crater. There have also been reports of lava rocks the size of cars, and villagers fleeing from a flood of boiling water. A 4km radius around the volcano was declared a red alert area by the Salvadoran Interior Ministry, while a "yellow alert" was issued for adjacent areas.
Approximately 10,000 people live in the area surrounding the volcano.
Ilamatepec volcano, also known as the Santa Ana volcano, in El Salvador has spewed lava and ash from its main crater.
At 1443 GMT the volcano, 66 kilometres west of the capital released a giant plume of smoke. Authorities ordered an evacuation of the immediate surrounding area.
"It has begun to expel magma on the side of the town of San Blas, while the ash is being carried by a south-south-westerly wind" - vulcanologist Francisco Barahona, University of El Salvador scientist.
Salvadoran authorities activated emergency plans on Tuesday as a western volcano, Ilamatepec ,continued to spew gas and vapour in what experts said was a "significant increase" in activity.
The renewed energy was first detected on Saturday, when experts from the National Service of Earth Studies witnessed 17 small earthquakes around the Ilamatepec volcano. On Monday, scientists began to observe incandescent rocks in a 2,150-square-foot area near where columns of gas and vapour reached to 3,280 feet.
"The volcano is showing a significant increase in activity, both in the number of seismic events as well as in the amount of energy being liberated" - Rene Figueroa, Salvadoran Interior Minister.
Figueroa said all emergency agencies were on alert, both keeping people informed and preparing for the evacuation of 20,000 people who live nearby if the activity increases even more.
Ilamatepec is located in a coffee-growing region of El Salvador about 40 miles west of San Salvador, the capital.