(NEXSTAR) — “Unprecedented amounts” of rainfall and flooding have kept Yellowstone National Park closed since Monday. According to National Park Service officials, parts of the park may remain closed for quite some time.

Floodwaters began ravaging Yellowstone National Park and the surrounding area Monday, washing out roads and bridges, cutting off electricity, and forcing thousands to evacuate. Officials say heavy rain and melting snowpack are responsible for the deluge.

The Yellowstone River crested at 13.88 feet Monday, surpassing the previous record of 11.5 feet that was set in 1918, according to the National Weather Service.

“It’s a lot of rain, but the flooding wouldn’t have been anything like this if we didn’t have so much snow,” said Cory Mottice, a meteorologist with the National Weather Service in Billings, Montana. “This is flooding that we’ve just never seen in our lifetimes before.”

As of Thursday, all entrances to Yellowstone remain closed. Even when the floodwaters recede, park officials believe the northern portion of the park will likely stay closed “for a substantial length of time due to severely damaged, impacted infrastructure.”

Aerial assessments showed major damage to multiple sections of roadway between the North Entrance to the park, Mammoth Hot Springs, Lamar Valley, and Cooke City near the Northeast Entrance. The road between Gardiner, Montana, and Cooke City will likely not reopen for the rest of the season, Yellowstone National Park Superintendent Cam Sholly explained during a press conference earlier this week.

“Many sections of road in these areas are completely gone and will require substantial time and effort to reconstruct,” park officials said in a release on Tuesday. “The National Park Service will make every effort to repair these roads as soon as possible; however, it is probable that road sections in northern Yellowstone will not reopen this season due to the time required for repairs.”

There may still be more damages in the park that officials haven’t yet seen. During a press conference earlier this week, Sholly explained high water was making it difficult to fully assess the damages.

In a statement Thursday, National Park Service Director Chuck Sams said the agency is “committed to working quickly to reopen as much of Yellowstone National Park as possible as soon as it is safe to do so.”

That would likely include opening the southern loop of the park, where visitors can visit Old Faithful, first. But, because “half the park cannot support all of the visitation,” Sholly said officials are evaluating options such as timed entry reservation systems. He added that he’s hopeful the southern loop can open “relatively soon.”

If you had already booked a stay with Yellowstone National Park Lodges, cancellation fees have been waived for reservations through June 30, 2022. Guests will receive a full refund, according to officials, and reservations can be canceled online.

“We realize there is much challenging work ahead, and we will do everything we can to support the park, partners, concessioners, and gateway communities on the road to recovery,” Sams said.

The Associated Press contributed to this report.