A preliminary magnitude-5.1 earthquake jolted Guye District of Tangshan City, north China's Hebei Province, at 6:38 a.m. Beijing time on Sunday, according to the China Earthquake Networks Center (CENC).

The epicenter was monitored at 39.78 degrees north latitude and 118.44 degrees east longitude, with a depth of 10 km, the CENC said. 

There are no immediate reports of damage or injuries, but tremors were felt in Beijing and Tianjin.

Emergency response work is being carried out in an orderly manner, according to the city government's information office. 

The province has launched a level III emergency response, the second lowest in China's four-tier emergency response system, for earthquakes.

Firefighters have been dispatched to the district. The railway department immediately launched an emergency plan to suspend passenger trains passing through the area, and is organizing a comprehensive inspection of railway equipment and facilities. 

A 7.8-magnitude quake jolted Tangshan in 1976 and killed more than 240,000 people. 

(With input from Xinhua)