He added that the magnitude 7.8 earthquake that struck Mindanao on June 8 may have loosened the soil in mountainous areas, while continuous rainfall saturated the ground, triggering landslides.
"Maari po 'yan. Kailangang imbestigahan itong maigi ng MGB (Mines and Geosciences Bureau) and PAGASA," Alejandro said, adding that reports of missing persons are still being validated.
"There were several injured individuals na reported pero mababa naman ito," he added.
Alejandro said the number of affected families has reached about 112,000.
"As of this morning, mayroon na tayong 112,000 families, more or less, na directly affected ng Habagat at Typhoon Inday coming from 404 barangays from Region 2, CALABARZON, Region 3, Region 5 hanggang Region 12, BARMM and Zamboanga," he said.
A total of 77 evacuation centers are currently sheltering about 2,900 families, or nearly 11,000 individuals. Meanwhile, around 7,000 families are staying outside evacuation centers and are being monitored by authorities.
The OCD has monitored 32 flooded areas, although Alejandro said the number could increase as the effects of the southwest monsoon are expected to persist until Monday.
"Today, heavy in Visayas, specifically Aklan, then tataas sa Luzon, Regions 4B, 4A, 3, even NCR hanggang Zambales, Bataan and even Region 1 tataas hanggang bukas and Monday," he said.
Alejandro also reported that 73 seaports had suspended operations as of Saturday morning after PAGASA raised a gale warning over the northern and eastern seaboards of Northern Luzon. Tropical Cyclone Wind Signal No. 2 remained in effect over northern Batanes (Itbayat), while Signal No. 1 was hoisted over the rest of Batanes, the Babuyan Islands, and the northern portion of mainland Cagayan.
As of Saturday morning, 305 passengers and 176 rolling cargoes were stranded due to the weather disturbance, he said.
Alejandro added that there were also reports of infrastructure damage in Mindanao.
