As Hurricane Irma lashes the Caribbean and heads toward Florida, delivery services have halted or reduced activity in affected areas.

Major shipping carriers—the U.S. Postal Service, FedEx Corp. and UPS Inc.—have been affected by the Category 5 hurricane, which is projected to hit South Florida by Sunday. Smaller delivery services that focus on perishable goods also are curbing their activity as the dangerous storm approaches. Irma as of Thursday afternoon continued to carry maximum sustained winds near 175 mph, with higher gusts, according to the National Hurricane Center.

Instacart, which delivers groceries and other online orders, says it is monitoring inventory of the retailers it works with to ensure product availability is as accurate as possible for Florida and the Southeast United States. Delivery capacity for Friday through Sunday in some areas has been reduced in anticipation of unsafe conditions, an Instacart spokeswoman says. “If those conditions do not present we will immediately increase delivery capacity.”

Water delivery is in high demand and several retailers have limited supply, she says. “We have noted in the Instacart app and on our website when water may be unavailable from a retail partner. While pricing for different brands of water varies, the price reflected in the Instacart app and on our website is set by the retail partner. Pricing differences are clearly noted in the Instacart app and on our website.”

The delivery service will communicate delivery capacity to customers via the Instacart website and app, and customers are encouraged to contact its community support team via phone or email for further information, the spokeswoman says. “Instacart staff and shopper safety is our highest priority. We will continue to provide service until it is no longer safe to do so. Our shoppers and delivery personnel have been instructed to cancel or re-route deliveries if unsafe conditions are present,” she says.

Instacart charges $5.99 for a one-time delivery and works with such retailers as Target Corp., No. 20 in the Internet Retailer 2017 Top 500, Costco Wholesale Corp. (No. 8) and CVS (No. 106). It also offers a plan called Instacart Express, which includes unlimited deliveries for $14.99 per month or $149 per year, for orders over $35.

Daphne Carmeli, CEO and founder of Deliv, says the same-day delivery service is working closely with its retailer clients and other businesses to plan appropriate shutdowns as Irma approaches. “Once this storm is past us, we look forward to offer our services to help everyone get back on their feet,” she says.

In an email sent Wednesday to its retail and other clients, Deliv said, “We have decided that it would be prudent for Deliv to cease [same-day delivery] operations as of tomorrow evening (Thursday) in some markets. At this time our plan is to suspend service in Miami and Fort Lauderdale for Friday, Saturday and Sunday. Forward-moving decisions remain for Tampa and Orlando, as well as about the length of the service suspension for all. Mother Nature, the path and extent of Irma’s damage, and the length of recovery operations will be the primary drivers in those decisions.”

Deliv last month announced expanded service and is now available in 33 markets, up from 19. Orlando and Tampa, Fla., were part of that expansion. Retailers that use Deliv set the prices for same-day delivery; Macy’s Inc. (No. 6), for example, charges $8 while Best Buy’s fee is $5.99.

The U.S. Postal Service says it is monitoring Irma and has suspended all operations for offices in the Florida Keys, including Priority Mail Express service and shipment of live animals. Operations are expected to be suspended through close of business Monday. Priority Mail Express service to Puerto Rico and the U.S. Virgin Islands continue to be suspended until further notice. USPS is the shipping carrier for 312 retailers in the Internet Retailer 2017 Top 1000.

FedEx Corp., shipping carrier to 318 retailers in the Top 1000, has temporarily suspended Express and Ground service in the Florida Keys and closed the following offices in South Florida: Miami, Ft. Lauderdale, Coral Gables and Pompano Beach. SmartPost service also remains on hold in the Keys and throughout Puerto Rico. SmartPost utilizes FedEx’s network for the initial leg of a parcel’s delivery and then hands off to the U.S. Postal Service for the final mile. UPS Inc., carrier to 421 retailers in the Top 1000, has a similar program called SurePost.

UPS, on its service alerts page, says mandatory evacuations ahead of the storm have halted pickups and deliveries in parts of South Florida, primarily in the Keys. “The hurricane has already caused service disruptions in Puerto Rico and other areas of the Caribbean,” UPS said.

Employee safety is top priority for all businesses in the path of Irma, and retailers with stores and fulfillment centers that may be in harm’s way should then ensure their inventory is safe, says Tushar Patel, chief marketing officer at Kibo, an order management, e-commerce and omnichannel technology vendor.

“With Hurricane Irma already making landfall in the Caribbean and projected to continue toward Florida and the East Coast, retailers in its potential path are faced with uncertainty of the impact this monster storm will bring,” Patel says. “The advantage of the omnichannel retail world we are in is that retailers do not need to be out of business when one channel is affected by natural disasters like Harvey or Irma. They can utilize their digital networks to best serve their physical networks and ensure they continue to offer their consumers the items they will need to recover from the storm.”