HELENA, Mont. (NEXSTAR) — Major flooding swept away at least one bridge, washed away roads and set off mudslides in Yellowstone National Park on Monday.

Officials closed all five entrances and began evacuating visitors from the northern part of the park, issuing an alert that the park was being temporarily closed due to “extremely hazardous conditions.”

Park officials said roads going in and out of the community of Gardiner, Montana, just north of the park are impassable. Superintendent Cam Sholly said the northern loop of the park could be closed for a substantial amount of time.

Park officials planned to start evacuating visitors from the southern loop of the park on Monday afternoon because more rain is in the forecast.

Predictions of flooding at higher levels, along with water and wastewater concerns, prompted the decision, Sholly said.

Helicopter video shared by the park shows a road completely washed out in several places by the river next to it. Park officials said in a statement that “unprecedented amounts of rainfall” caused the flooding.

The park entrances will remain closed at least through Wednesday.

“We will not know timing of the park’s reopening until flood waters subside and we’re able to assess the damage throughout the park,” Sholly said. “I appreciate the efforts of the Yellowstone team and partners to safely evacuate areas of the park and of our gateway community partners who are helping us through this major event.”

For updated conditions, visit Park Roads or receive Yellowstone road alerts by texting “82190” to 888-777.

The Associated Press contributed to this report.