Ecuador's strongest earthquake since 1979 has killed at least 41 people, caused severe damage and prompted the government to declare a state of emergency, dpa reported. The 7.8-magnitude quake struck the north-western part of the country at 7:58 pm (2358 GMT) Saturday, the US Geological Survey said. Its epicentre was 20 kilometres underground and about 170 kilometres north-west of the capital Quito. Vice President Jorge Glas said in a televised address that 41 people have died and that the toll was expected to rise as relief agencies have been unable to reach the worst-hit areas. There were some 50 aftershocks in the first four hours after the quake first hit, the vice president said. Glas, who is leading the country in the absence of President Rafael Correa, said the armed forces and national police were put on maximum alert. Some 16 people were reported dead in the city of Portoviejo, 10 in the coastal city of Manta and two in the province of Guayas, Glas said. Some 71 houses had collapsed in the coastal city of Esmeraldas near the epicentre, according to El Telegrafo newspaper. Electricity went down in parts of Quito, according to El Telegrafo. The quake came as a result of movement at or near the plate boundary between the Nazca and Pacific plates, USGS said.