In the worst affected San Marcos department in Guatemala, about 155 people were injured and 135 houses were destroyed, according to its governor Aroldo Rivera.
Guatemalan President Otto Perez Molina said about 100 others were missing.
The 7.4-quake quake struck at 1635 GMT, with its epicentre in the Pacific Ocean, some 24 km from Champerico municipality in Guatemala, the US Geological Survey (USGS) said.
Thousands of Guatemalans rushed to the streets in fear of new earthquake. Public buildings have been evacuated, and some 73,000 homes were left without electricity.
Relief agencies said the toll could rise.
The powerful quake caused damage in several other places in Guatemala, including Quetzaltenango and Solola departments, and the capital Guatemala City, Xinhua reported.
It also triggered landslides in various places.
The authorities, however, have ruled out a tsunami.
Molina said 2,000 troops have been deployed to assist in relief efforts.
In neighbouring Mexico, the intensity was recorded at 7.3 on the Richter scale. Thousands of people in Mexico City were evacuated from the offices and schools.
The tremor also prompted evacuation orders in El Salvador.
This was the strongest quake to hit Guatemala since Feb 4, 1976 when a 7.5-magnitude tremor left nearly 23,000 people dead and over a million homeless.