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MIAMI (CBSMiami) — Miami-Dade County has declared a local state of emergency ahead of category-5 Hurricane Irma and is starting evacuating zones as soon as Wednesday.

“Hurricane Irma poses a serious threat to Florida, South Dade and our area in particular,” said Miami-Dade Mayor Carlos Gimenez.

The mayor said they may be asking residents in evacuation zones A and B to start evacuating as early as Wednesday. They will start evacuating special needs residents Wednesday morning. Click here for a map of evacuation zones.

“This is a powerful storm which poses a serious threat to our area,” said Gimenez.

All county offices will be closed Thursday and Friday.

The mayor asked residents to have enough supplies to be prepared.

“County tap water is safe to use,” said Mayor Gimenez.

The mayor had a message for those visiting the Sunshine State – consider cutting your plans short.

Miami-Dade Transit will remain open until Tropical Storm force winds are felt in the county. That should be as early was Friday.

The mayor is asking residents to not cut down any trees and just focus on picking up loose items that could become dangerous flying projectiles during the hurricane.

As for schools, Miami-Dade Public Schools Superintendent Alberto Carvalho has cancelled school for Thursday and Friday.

“This is a storm that could not and should not be ignored,” said Carvalho. “We have decided to err on the side of caution and declare schools to be closed both Thursday and Friday.”

All school activities are cancelled across Miami-Dade county for Thursday and Friday.

“Only essential personnel will be expected to work Thursday and possibly Friday,” said Carvalho.

The only educational programs that will be open on Wednesday are after-school care for the very young.

“We are asking parents to pick up their kids on time tomorrow at the after school program,” said Carvalho.

Meantime, Miami-Dade residents stocked up on their supplies – filling their baskets with water and food including Brittany and Luis Velzquez who were at a Miami Gardens Walmart.

“It’s category 5…we should prepare…be ready,” said Brittany.

Long lines could be seen in various Miami-Dade stores. Shopper Jesus Tavares says you cant feel the urgency.

“You feel it from everywhere..even in the highway,” said Tavares.

Locals are advised to stay alert and prepared. Miami-Dade County offers a variety of apps and alerts to stay up to date. You can sign up for Miami-Dade Emergency Alerts  that will let you know through email or texts about public safety issues, recommended public protective actions, or other emergency information. Their SAFE app lets users find open and available evacuation centers and Disaster Assistance Centers near you. To report damage info to the county, click here.