Thirteen others were injured when the Tungurahua volcano near the town of Penipe erupted on Thursday.
Juan Salazar, Penipe's mayor, told Ecuavisa television: "The situation is indescribable. There are approximately 60 people missing in the highest-risk area, as well as seven wounded people who were taken to the city of Riobamba and six others wounded in Penipe."
One man's body was recovered after the overnight eruption of lava from Tungurahua, Salazar said.
It is the volcano's most powerful eruption since 1999, local officials said.
Salazar said areas surrounding the volcano were badly affected by lava and flames from the 5,029m (16,499ft) volcano, 135km (83 miles) south of Quito.
"There was a very powerful explosion this morning, which produced incandescent rocks, ash and lava that devastated several areas," Salazar said.