Vice President Leni Robredo postponed Monday the release of her report on the government's war on drugs after a magnitude 6.9 earthquake struck in Davao del Sur, the fifth earthquake above magnitude 6.0 to hit Mindanao since October.

"Minabuti namin na ipagpaliban muna...Panahon na ito na magkaisa tayo," she said, adding she received word that at least 8 to 10 people were killed in Sunday's quake.

She urged the public to donate tents and drinking water for affected residents, saying many people in Mindanao have been traumatized by the series of temblors.

Speaking to radio DZMM, Robredo said she is still consulting her team on the best time to go to Davao.

"Tinitingnan natin. Unang-una, 'yung gastos, itulong na lang natin. Pangalawa, aasikasuhin pa tayo ng mga opisyal dun. So dapat sana, busy sila ngayon eh. Tantiyahin natin pero ang team natin ay ready kahapon pa. Hinintay lang namin 'yung listahan ng kailangan at ngayon kailangan nila tent at drinking water," she said.

Renato Solidum, head of the Philippine Institute of Volcanology and Seismology, said the quake could have been caused by the Tambulan Fault, which has a "low" chance of generating another tremor with a maximum magnitude of 7.2.

Some 442 aftershocks, the strongest of which is magnitude 5.2, have hit the region as of 4 a.m. Monday, he said.