The first official hurricane warnings were issued for Florida by the National Hurricane Center late Thursday evening as the storm continues to draw closer to the U.S.

South Florida and the Florida Keys were both issued hurricane warnings and storm surge warnings as the National Weather Service sent out its 11 p.m. update on Thursday.

"A Storm Surge Warning means there is a danger of life-threatening inundation from rising water moving inland from the coastline, during the next 36 hours in the indicated locations," the NWS said in its newest warning.

Hurricane Irma is currently "pummeling" Turks and Caicos with powerful winds, according to the National Hurricane Center's latest advisory. It is located about 585 miles southeast of Miami and should make landfall in South Florida on late Saturday or early Sunday.

The record Category 5 storm, which skirted north of the Dominican Republic early Thursday, has set its sights on South Florida after leaving a trail of death and destruction in the Caribbean. At least 13 people have been killed.

Irma, dubbed the most powerful Atlantic storm in a decade, had maximum sustained winds of 165 mph on Thursday evening as it moved further away from the northern coast of Puerto Rico and over the Dominican Republic and Haiti. The wind speeds had dropped from the day before by about 20 mph.

"Some fluctuations in intensity are likely during the next day or two, but Irma is forecast to remain a powerful Category 4 or 5 hurricane during the next couple of days," the National Hurricane Center said in its advisory.

As of 11 p.m. ET on Thursday, Irma was moving at 16 mph and was located about 55 miles east-southeast of Great Inauga Island, the southernmost island in the Bahamas, where the storm was expected to hit Thursday night. Much of Turks and Caicos and the Bahamas could get 8 to 12 inches of rain, with up to 20 inches in isolated spots through Saturday. A storm surge could bring water levels up to 20 feet above ground in Turks and Caicos.

A storm surge could also reach 5 feet on the northern coast of the Dominican Republic where Irma swept by on its way to Turks and Caicos.

Millions of children in Haiti and the Dominican Republic are at risk, according to Save the Children organization.

“Deadly storms have a bias against children. Storms often leave a lasting impact on young minds. Relief efforts should prioritize children – their needs, their emotional well-being,” Unni Krishnan, director of Save the Children's emergency health unit, said in a statement Thursday.

Florida Gov. Rick Scott, who declared a statewide emergency earlier this week, has warned that the "massive storm" could be more treacherous than Hurricane Andrew, which devastated the Sunshine State 25 years ago.

"I want everybody to understand the importance of this. This is bigger than Andrew," Scott said Wednesday in an interview from Tallahassee with ABC News' "Good Morning America" co-anchor Robin Roberts. "This could be worse."

At a press conference Thursday, Scott said Irma could bring "life-threatening" damage to Florida and he urged residents on the state's east and west coast to be prepared to evacuate and to heed warnings from local officials, saying a storm surge could bring water levels up to 10 feet above ground.

"This could impact any part of our state," Scott told reporters. "We'll be doing evacuations, but everybody's got to listen."

Scott said he expects additional evacuation orders will be given once the storm gets closer.

Mandatory evacuations have already been ordered for parts of several Florida counties, including Brevard County, Broward County, Indian River County, Lee County, Martin County, Monroe County, Miami-Dade County, Palm Beach County, St. John's County. Most of the mandatory evacuation zones were issued for barrier islands, coastal areas and for those living in mobile homes.

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