MEXICO CITY – A powerful earthquake struck offshore in Mexico's Gulf of California on Thursday, causing people to flee into the streets in the western state of Sinaloa, but there were no reports of damage or injury.

The U.S. Geological Survey initially reported the magnitude of the quake as 6.9, but later in the day revised it to 6.7. It hit at 11:53 a.m. (1:53 p.m. EDT, 1753 GMT).

The tremor struck about 72 miles (116 kilometers) south of Los Mochis, a city just inland from the coast in Sinaloa. It was centered at a relatively shallow depth of 5.6 miles (9 kilometers).

Sinaloa civil protections authorities said there were no reports of injuries or damage.

Alberto Montoya Rodriguez, who runs the losmochis.com website from his home in Ahome, north of the city, said the ground seemed to shake for more than a minute, sending him and his neighbors into the streets.

"There was a lot a panic," he said, but there was no damage beyond "just a big scare."

Alejandra Cruz, a worker who answered the telephone at the Best Western Hotel in Los Mochis, said employees and guests were evacuated but returned to the building shortly after.

"We had customers in the restaurant that took to the streets," added Sujey Becerra, an employee of Las Fuentes Los Mochis, another hotel in the city.

In the city of La Paz, in Baja California Sur, authorities also reported panic, but said there was no damage or injuries.

Alfonso Gomez, assistant director of civil protection in La Paz, told The Associated Press by telephone that some schools and public buildings were evacuated, and city offices received calls from alarmed residents.

The same region was hit by three moderately powerful earthquakes ranging in magnitude from 5.5 to 5.8 Tuesday night and early Wednesday, but they caused no known damage.