Frantic locals poured out of buildings into the streets after homes and office buildings took a solid jolt.
"It really shook me right through to the soul of my body," one government employee told AFP. Tremors were felt across most of the island.
The United States Geological Survey (USGS) said the quake, with a depth of some 10 kilometers (6.2 miles) struck the Caribbean island at 1423 GMT.
McClearly Frederick with Hazard Management Cayman Islands said however the worst of the earthquake was over and that it was not considered a major temblor.
A 6.8 magnitude earthquake was the last quake Cayman experienced back in December 2004.
The USGS said the quake, one of several to hit South America and the Caribbean in recent days, struck some 52 kilometers (32 miles) east-southeast of Bodden Town on Gran Cayman.
It struck one week after a massive 7.0-magnitude quake hit Haiti, leveling the capital city of Port-au-Prince and surrounding towns and villages, killing as many as 200,000 people according to some preliminary estimates.