"Public activities are suspended and we recommend that all buildings be evacuated. We await official data and information in order to provide necessary assistance to all those affected," said the president.
At least five landslides hit the American Highway.
Communication Minister Alejandro Sinibaldir told Xinhua that there are roadblocks and the worst happened in the highway to San Marcos and was expected to be cleared in 24 hours.
Power failures and house collapses were reported in different parts of the country, according to local daily of Prensa Libren.
The quake was also felt in Mexico and Salvador, activating alarms in these countries.
In Mexico City, thousands of people left offices and schools under evacuation plans.
Mayor Marcelo Ebrard said on his twitter account that the quake was felt apparently in parts of the Mexican capital. He said no damage has yet been reported but evacuations are necessary.
In El Salvador, dozens of people went out to the streets after the earthquake. The quake hit San Salvador with an intensity of four on the Mercalli scale, which ranges from one to 12.
So far neither the Salvadoran authorities nor the relief agencies have reported casualties or damage.
This is the strongest earthquake that has ever happened in Guatemala since Feb. 4, 1976, when a 7.5-magnitude earthquake left nearly 23,000 dead, 76,000 wounded and more than 1 million others homeless.
Landmark building should respect the public's feeling