Online retailers in Hurricane Harvey’s path are feeling the impact of a storm that has left much of Houston underwater.

Many Houston-area roads are impassable because of flooding or downed trees and wires, and the city’s two major airports remain closed. Harvey hit the Texas coast Friday night as a Category 4 hurricane with winds of 130-156 mph, which combined with record rainfall, has produced severe damage across the region.

Houston-based women’s apparel and accessories retailer Francesca’s Holdings Corp., No. 658 in the Internet Retailer 2017 Top 1000, posted a weather advisory on its website notifying shoppers that their online orders might be delayed due to flooding caused by Harvey. The retailer’s customer service is also closed due to the weather.

Danny Gavin, vice president and director of marketing at Houston-based online jeweler Brian Gavin Diamonds (No. 781), says the roads were so bad on Sunday and Monday that his employees weren’t able to get to the office. The retailer’s phone system went offline Monday, and both UPS Inc. and FedEx Corp. have suspended service to large swaths of the Houston metropolitan area and parts of southwest Louisiana.

Still, orders must get out the door, and Gavin says he and his team are trying to figure out exactly how to do just that. “There are some orders that must ship on Wednesday,” he says. “We have spoken about driving to a nearby city to ship packages. The issue is a lot of the roads are still flooded, so it’s really not safe right now.”

Brian Gavin Diamonds’ offices are on the 18^th floor of a high-rise office building, so the company has been spared any flooding. Its website and customer database are hosted in the cloud, so the retailer hasn’t seen a site disruption, he says.

“Thankfully we have some personnel in other cities, so they are able to help hold down the fort,” he says. “As for local Houstonians—we care about their safety and their family’s safety first. After that—if they have power and internet—we are asking them to do their best to work from home.”

Phastek Performance LLC (No. 934), an online retailer of parts for Chevy Camaros, posted on its Facebook page Monday morning that flooding was making it difficult for its staff members to get to its office, and it warned shoppers about potential order delays. By Tuesday afternoon however, the retailer posted an update notifying shoppers that the company is up and running and processing orders.

Phastek closed its offices early Friday in advance of the storm’s landfall so that employees could adequately prepare their families and homes. The company could not immediately be reached for comment about Harvey’s impact on business.

Smaller retailers weren’t the only ones affected by Harvey. Amazon.com Inc. (No. 1) closed its Houston-area facilities due to the storm.

“Customers in the flood-impacted areas should expect delays in receiving their Amazon orders until the floods subside,” an Amazon spokeswoman says. “We are continuing to check in with employees to confirm their well-being and safety, and our facilities have been minimally impacted by the floods or storm.”

Parcel and mail delivery by the U.S. Postal Service has been disrupted, but USPS says the mail is “secure and safe,” with decisions about delivery being made “on a location-by-location basis, depending on the severity of conditions.”

“The Postal Service activates it continuity of operations plan to offload mail at designated sites for impacted processing centers and, as necessary, for post offices,” USPS said in a statement. “Additionally, using service alerts, we notify commercial mailers that we are unable to accept drop shipments but redirect in accordance with those plans.”

UPS service disruption alerts as of Tuesday afternoon included 728 ZIP codes in Texas and four in Louisiana, according UPS.com. For FedEx, Express service as of Tuesday afternoon had been temporarily suspended in 681 ZIP codes in Texas and 19 in Louisiana, according to its website. FedEx Ground was offering partial service, dependent on conditions, in nearly 597 Texas ZIP codes and 381 in Louisiana as of Tuesday afternoon.

UPS is the shipping carrier for 421 retailers in the Top 1000, FedEx for 318 and USPS for 312, according to Internet Retailer’s Top500Guide.com.

“Our priority is always the safety of our team members and providing service to our customers. FedEx has implemented contingency plans to lessen the effect of Hurricane Harvey on operations and mitigate potential service delays. We are also supporting organizations such as Direct Relief, American Red Cross and Heart to Heart, which are providing necessary supplies to those impacted by the storm. We encourage customers to check the status of their shipments at http://fedex.com,” FedEx said in a statement.

As Harvey approached Texas, UPS says its first priority was to ensure the safety of its employees and facilities, which meant evacuating its workers from the cities of Corpus Christi and Victoria, and then Houston as the storm moved inland and flooding began. UPS facilities across the country are absorbing traffic that might otherwise go through the Houston area, a spokesman says. Teams on the ground in the local areas are determining the best way to hold or reroute parcels, and UPS has been communicating with shippers about service delays, he says. The UPS Foundation on Monday pledged $1 million toward recovery efforts in Texas and Louisiana in the form of cash grants, in-kind transportation movements and technical expertise.

Amazon and other retailers also are pitching in financially to help Houston, the nation’s fourth-largest city, recover.

Among the retailers that are donating to hurricane relief efforts:

• Amazon and Whole Foods are combining to match up to $1 million in cash donations made through Amazon to the American Red Cross.
• Wal-Mart Stores Inc. (No. 3) announced Friday plans to donate a minimum of $1 million in the form of cash and other product donations.
• The Home Depot Inc. (No. 8) said Monday it is pledging $1 million. Home Depot also has a link on its home page where shoppers can donate to the American Red Cross to help those affected by Harvey.
• Target Corp. (No. 20) on Tuesday announced it is donating $500,000 to disaster relief organizations that work with Harvey victims.
• Lowe’s Cos. Inc. (No. 25) also had a link on its home page where shoppers could click through and donate to the American Red Cross.
• Neiman Marcus (No. 41) has a link to the American Red Cross on its home page. A spokeswoman says the retailer also donated $50,000 to the Hurricane Harvey Relief Fund. The retailer’s Houston location has been closed since 6 pm on Friday.
• Preppy apparel retailer Vineyard Vines notified shoppers via email on Tuesday that it is donating all profits from its Texas flag T-shirt to the Hurricane Harvey Relief Fund.