Puerto Rico governor: Still time to get to shelters before Hurricane Maria

(CNN)There is still time for Puerto Ricans to get to a government-run shelter before powerful Hurricane Maria clobbers the island, Gov. Ricardo Rosselló told CNN late Tuesday.

But the window of opportunity is closing.

"There's still time ... but people need to move fast," Ricardo Rosselló told CNN's "Anderson Cooper 360˚," calling the storm the "worst hurricane in modern history in Puerto Rico."

US President Trump tweeted his thoughts to those on the island, a US territory. "Be careful, our hearts are with you," he wrote, calling the storm a "monster hurricane," and pledging assistance.

Maria is a Category 5 storm with sustained winds of 175 mph (281 kph). By late Tuesday, the eye of hurricane was expected to move near or over St. Croix in the US Virgin Islands and make landfall in Puerto Rico Wednesday morning.

"Winds are starting to pick up, the glass is starting to bow back and forth. We're soon going to take shelter in a safe room," Mike Theiss, a hurricane chaser who is staying in Fajardo, told CNN's Don Lemon.

Maria has already obliterated parts of Dominica and killed at least one person in Guadeloupe.

Rosselló said there are about 500 shelters open. Emergency workers are still out, but will head in when sustained winds reach 50 mph, the governor said

Many people live on the eastern half of Puerto Rico, which forecasters worry will endure the brunt of the most powerful hurricane ever to hit the island.

Residents of Puerto Rico, who were spared some of Irma's wrath when that hurricane's core passed north of the island, boarded up homes and businesses Tuesday. People who fled to the US territory as Maria, and before it, Hurricane Irma, which swept through the region just days ago, advanced on their islands sought refuge in hotels and shelters.

Cars line up at a gas station in Santurce, Puerto Rico, on September 19.

Photos: Hurricane Maria hits the Caribbean

Cars line up at a gas station in Santurce, Puerto Rico, on September 19.

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A motorist drives on the flooded waterfront in Fort-de-France, Martinique, on September 19.

Photos: Hurricane Maria hits the Caribbean

A motorist drives on the flooded waterfront in Fort-de-France, Martinique, on September 19.

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Floodwaters surround cars in Pointe-a-Pitre, Guadeloupe, on September 19.

Photos: Hurricane Maria hits the Caribbean

Floodwaters surround cars in Pointe-a-Pitre, Guadeloupe, on September 19.

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Soldiers patrol a street in Marigot, St. Martin, as preparations were made for Maria on September 19.

Photos: Hurricane Maria hits the Caribbean

Soldiers patrol a street in Marigot, St. Martin, as preparations were made for Maria on September 19.

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People buy provisions in Petit-Bourg, Guadeloupe, as the hurricane approached on Monday, September 18.

Photos: Hurricane Maria hits the Caribbean

People buy provisions in Petit-Bourg, Guadeloupe, as the hurricane approached on Monday, September 18.

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Customers wait in line for power generators at a store in San Juan, Puerto Rico, on September 18.

Photos: Hurricane Maria hits the Caribbean

Customers wait in line for power generators at a store in San Juan, Puerto Rico, on September 18.

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Waves crash in San Juan, Puerto Rico, as Hurricane Maria nears the island on Tuesday, September 19. Maria is churning through the Caribbean, threatening islands that were already crippled <a href="http://www.cnn.com/2017/09/07/americas/gallery/hurricane-irma-caribbean/index.html" target="_blank">by Hurricane Irma</a> earlier this month.

Photos: Hurricane Maria hits the Caribbean

Waves crash in San Juan, Puerto Rico, as Hurricane Maria nears the island on Tuesday, September 19. Maria is churning through the Caribbean, threatening islands that were already crippled by Hurricane Irma earlier this month.