The two-storey building, a jeweller's shop, was in the centre of the historic town, that lies about 57 kilometers (36 miles) east of the quake's epicentre, police said.

"The whole town shook and the building came down, it was horrible," said Brandy Wilson, who works at the Best Western hotel in the town. "They're telling us that they are still people trapped inside."

Paso Robles appeared to suffer the brunt of the damage caused by the biggest earthquake to hit the area in years.

Elsewhere in the region, only minor damage and injuries were reported in the temblor and its wave of aftershocks.

Other damage was done to buildings in scenic Paso Robles, television pictures showed.

TERRA.WIRE