About 600 people, mostly labourers, huddled at the West Salalah School, some sleeping on mattresses on the floors of classrooms, where math and English lesson posters hung on the walls.
"The fourth is a young Omani man who was swept away in his vehicle by flooding", he added.
Among those missing on the Arabian Sea isle are Yemenis, Indians and Sudanese citizens, and officials feared some may be dead.
Salah is home to about 2,00,000 people and portion of it lost power after being hit by the storm.
Salalah and the surrounding area received almost 278mm of rain, almost three times its annual amount.
Now it is known about two dead in Yemen and four in Oman, including a 12-year-old girl and an Asian immigrant.
Tropical cyclone "Mekunu" is unlikely to reach the UAE, but the eastern and southern parts of the country might be affected by a moist air mass, according to the medium-range forecast issued by the National Centre of Meteorology, NCM.
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The storm earlier hit Yemen's island of Socotra, causing deaths and widespread damages.
In Salalah, the heavy rain had nearly stopped on Saturday, an AFP photographer said, but many streets were still under water and nearby valleys were flooded.
India's Meteorological Department said the storm packed maximum sustained winds of 170-180 kilometres per hour with gusts of up to 200kph.
Oman's Public Authority for Civil Aviation stated that the nation's Marmul Airport will reopen Sunday after being closed since Thursday, as officials assess widespread damage in the country.
Socotra's governor Ramzy Mahrous said five Yemenis had died on the island apart from the two Indians.
"It was a scary feeling, as if it was the end of world", Mohammed Omer Baomer, an Omani resident, told AP.
Yet even as Mekunu barreled overhead, the eye of the storm provided a moment's respite early Saturday morning.