New Delhi, Aug. 5 -- Guatemala remained on alert Tuesday after evacuating villages during an eruption of the Fuego volcano, one of Central America's most active.

About 1,700 people remained in shelters with the evacuations to stay in place until conditions improve, according to the country's disaster agency CONRED.

Officials raised the alert level to red in Sacatepequez, Escuintla and Chimaltenango, where about 29,000 people are affected by ashfall and schools remain closed. Authorities warned the next 72 hours were critical on Tuesday, as mudflows up to 7 kilometers (4.3 miles) long continue descending from the volcano, with incoming rain expected to increase the risk of additional volcanic mudflows.

Mudflows have not reached villages...