MANILA, Oct. 10 (Xinhua) -- A magnitude 7.4 earthquake struck off the coast of Davao Oriental province in the southern Philippines on Monday morning, killing at least six people and causing widespread damage to homes, buildings, and infrastructure, authorities have said.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said the quake occurred at 9:43 a.m. local time (0143 GMT) at a depth of 23 km, approximately 43 km northeast of the municipality of Manay.

Ednar Dayanghirang, regional director of the Office of Civil Defense (OCD), said three were killed in Mati City, one in Davao City, and two in Pantukan, a mining town in Davao de Oro province.

The Davao City Disaster Risk Reduction and Management Office confirmed the fatality and said that 347 people were treated for fainting or minor injuries.

"All patients have received proper medical attention and are now in stable condition," the agency said on social media on Friday afternoon.

Social media users shared their experiences, describing the tremor as sudden and violent, causing widespread panic.

The Mindanao Sentinel posted a video on social media, showing extensive damage to several buildings at a high school.

Local news outlet reported that the streets of Davao City on Friday afternoon were almost empty, as many public transport vehicles stopped plying their routes after the local government ordered the suspension of work and classes to facilitate a rapid assessment of all structures.

The suspension stranded many students, prompting police to deploy mobile patrol units to transport commuters home at no cost.

Phivolcs said the earthquake was felt across parts of southern and central Philippines. Due to its offshore epicenter, a tsunami warning was briefly issued for some coastal areas. The alert was lifted after further evaluation showed no significant threat of coastal inundation.

A new offshore earthquake with a magnitude of 6.8 struck Davao Oriental province on Friday night, Phivolcs said.

In a report, the institute said that the second quake, which occurred at 7:12 p.m. local time, struck at a depth of 37 km, approximately 43 km southeast of the municipality of Manay. The institute initially reported the magnitude of the second tremor as 6.9.

The latest two strong earthquakes come just 10 days after a magnitude 6.9 earthquake struck Cebu province in the central Philippines on Sept. 30, killing 74 people and injuring 559.

The Philippines has frequent seismic activities due to its location along the Pacific "Ring of Fire." ■