MEXICO CITY (Reuters) - A powerful earthquake that struck in the Gulf of California shook buildings and sent people running outdoors across parts of northern Mexico on Friday, but there were no immediate reports of damage or casualties.

The U.S. Geological Survey said the quake measured at 6.3 magnitude, after initially reporting it at 6.6. The epicenter was 48 miles (77 km) north-northeast of the town of Loreto in the state of Baja California Sur, the USGS said.

“It felt really awful,” said Rosita Ibarra, 34, a hotel worker in the city of Huatabampo in the state of Sonora. “I’m still in shock because I was alone at the reception and suddenly I couldn’t believe it, I saw the desk moving, and I ran.”

Mexican federal emergency services said there were no immediate reports of damage and ruled out a tsunami risk. Mexican President Enrique Pena Nieto confirmed on Twitter there were no initial reports of casualties.

Miguel Diaz, who works at a hotel in the city of Los Mochis, Sinaloa state, about 100 miles (166 km) south of Huatabampo, said he felt light tremors and saw lamps sway.

“We checked the rooms and saw that they were all in order, but thank god, everything was OK,” he said.