Tropical Cyclone Shaheen bore down on Oman on Sunday (October 2), killing at least three people.
It prompted authorities to delay flights to and from the capital, Muscat.
And urge residents to evacuate coastal areas.
One child who had been swept away by water was found dead, the state news agency said, and another person was missing.
Two workers were killed when a hill collapsed on their housing area in an industrial zone as a result of the cyclone, the state news agency reported.
Video footage from local broadcasters showed vehicles submerged as people tried to make their way through the muddy brown floodwater.
The eye of the storm was about 40 miles from the capital and it was carrying top winds of 75 mph or more, according to a joint statement by the country's hazard, weather and civil aviation agencies.
The storm's center was expected to hit land during the late afternoon and evening.
With it, will come very high winds and heavy rainfall.
Though the outer bands of the system were already being felt.
More than 2,700 people were put up in emergency shelters.
Most of the country's five million people live in and around Muscat.
Authorities said roads in the capital would be open only to vehicles on emergency and humanitarian journeys until the storm dies down.