Maria was earlier designated a category five status but weakened to category four when it entered Puerto Rico and waned subsequently, to category two, when it made exit.
So far, no deaths have been reported, but it is expected to change as communication is restored.
"When we are able to go outside, we are going to find our island destroyed," Abner Gómez, head of the disaster management agency was quoted as saying by the local El Nuevo Dia newspaper.
"It's a system that has destroyed everything in its path," Gómez added.
A curfew has been issued in the island by Governor Ricardo Rossello.
Residents have been ordered to stay indoors from Wednesday till Saturday morning.
Hurricane Maria is the strongest storm to hit the island in almost nine decades.
How to deem the category of a storm:
There are five categories in the Saffir-Simpson Hurricane Wind scale.
Category One: Wind speed upto 153 km/hr. Slight damage and power cuts.
Category Two: Wind speed 154-177 km/hr. Significant damage.
Category Three: Wind speed 178-208 km/hr. Building suffering major damage.
Category Four: Wind Speed 209-251 km/hr. Trees blown over. Building suffering major damage.
Category Five: Wind Speed 252+ km/hr. Trees blown over. Building suffering major damage. Major roads cut off.
Image: Screengrab from trendingallday.com
- Caribbean sees first regional launch of global plan on early warning systems
- Revive and restore wetlands, home to 40 per cent of all biodiversity
- 3 die in New Zealand’s Auckland amid floods: Reports
- Climate crisis and migration: Greta Thunberg supports IOM over ‘life and death’ issue
- Magnitude 5.9 earthquake hits Nepal, tremors felt in New Delhi