As Hurricane Irma continues toward Florida, people potentially in the storm’s path have been rapidly booking flights and changing existing flights to leave town earlier. As a result of the ticketing surge, airlines’ dynamic pricing models are presenting some customers with flight options that cost thousands of dollars more than usual, leading to accusations of price gouging.

Over the past couple of days, people searching for any remaining flights out of Southern Florida airports have been posting screenshots to Twitter of their highly inflated potential itineraries. One woman using Expedia was shown a Delta itinerary between Miami and Phoenix for $3,258. (Delta later directly reached out to her and she was able to book a seat at a lower price.) Someone else trying to book on American found their flight jumped almost $600 within the span of a couple hours. Another on United’s website was presented with a round trip fare between Miami and Denver for $6,785.

Hey @united this is price gouging. There was word you were going to add flights to help people get out of Miami, but this is ridiculous. pic.twitter.com/0qtEDKtEYb — Cindi Avila (@ChefCindi) September 6, 2017

So, what’s going on? Are the airlines price gouging people who are trying to get out of Hurricane Irma’s way? “This is what happens when thousands of people want to leave a place all at once,” says Seth Kaplan, managing partner of Airline Weekly. Kaplan, who is a Florida native himself, says the prices are due to website algorithms that automatically adjust fares in real time. The algorithms take into account a complicated structure of not only how many tickets are left at different fare and travel classes, but what others are offering similar flights at, and of course, supply and demand.

It’s this last portion that’s impacting people trying to leave Florida the most. The final few tickets are the most expensive on any flight for a number of reasons: perhaps only first class is left, lower fare classes have run out, or it’s likely the flight will be overbooked. People are now running into a combination of all of these problems as they try to book last-minute flights out of Florida, all around the same time. Additionally, according to Kaplan, unfortunate timing is also at play. “It’s a low-travel period after Labor Day,” he says, “so there were already less seats available now than last week. You’re facing a lower supply and surging demand.”

It’s a worst-case scenario for automatic airline systems

It’s basically a worst-case scenario for automatic airline systems that are presenting, very literally, the last few seats available on flights. (Kaplan even notes that smaller, regional airlines like Allegiant that aren’t listed on services like Kayak are also mostly sold out.)

What can airlines can do in this type of situation? Some have added additional flights, but there’s only so much that can logistically be done within such a short window of time. “It’s like Christmas,” says Chris Lopinto of ExpertFlyer.com, “except instead of having five months to figure things out, you’re trying to figure this out over the course of five days.”

Lopinto also says airlines can file different fares every hour, so they have the ability to bring down the price for tickets. Some airlines have committed to capping the prices of remaining direct flights. JetBlue and American both said they are selling remaining direct flights this week for $99, while Delta is capping direct flights at $399. These flights, though, were already sold out or nearly sold out. As of 4:21PM ET, ExpertFlyer.com showed just one seat available on JetBlue from Fort Lauderdale to New York over the next couple of days.

Though good luck finding a seat. There is nearly zero availability on any FLL-NYC flight tomorrow or Friday pic.twitter.com/uFjEPDpFYB — Jason Rabinowitz (@AirlineFlyer) September 6, 2017

United hasn’t said it will also cap prices, but it does appear they have started filing different fares. While on the phone with Lopinto, he looked up the same Miami to Denver flight that was found earlier at a price of $6,785. It was now listed at just above $700. Five minutes later, when he searched again, it was gone. Someone bought it.

Ultimately, even with the extra push from airlines, there simply aren’t enough seats available. If you still need a flight, look now, or start planning to drive.