A magnitude 6.3 earthquake struck the Philippines main island of Luzon on Monday and several people were killed in collapsed buildings, media reported.

The quake struck 60 km (37 miles) northwest of the capital, Manila, at a depth of 40 km (25 miles), the US Geological Survey (USGS).

The governor of Pampanga province told a radio station that several people had been killed. Media reported some structures had collapsed and the Clark International Airport, a former U.S. military base, had suffered some damage and had closed.

Tall buildings swayed in Manila's main business district and some people evacuated their offices.

The Philippines is on the seismically active Pacific "Ring of Fire", a horse-shoe shaped band of volcanoes and fault lines circling the edges of the Pacific Ocean.