The National Park Service might have to make do without hundreds of seasonal employees this spring and summer because of a hold placed on those positions by the Trump administration.

The Washington Post reported Friday that about 400 job offers have been rescinded. National Parks Traveler reported that the number was closer to 1,400 positions.

The National Park Service, which typically hires about 7,500 seasonal employees for peak tourism seasons, had not issued a statement regarding the issue at the time of this post.

The move apparently was part of a national hiring freeze announced by Trump on Monday, despite claims by the Office of Management and Budget that seasonal jobs would be exempt.

Kristen Brengel, senior vice president at the National Parks Conservation Assn., told National Parks Traveler that “people all over the country who had been hired as seasonals for many, many parks got a notification over email that their job offer that they had was rescinded.”

Brengel expressed “extreme concern” that the National Park Service will not be able to adequately fulfill the needs of visitors without seasonal employees.

“If they don’t fill the positions that had been opened, this could be so problematic for the parks,” Brengel said.

Seasonal employees fill many critical roles, from park ranger to traffic control to park maintenance to visitor services.

The Washington Post obtained a form email from the NPS, issued to seasonal employees. It reads:

“Your job offer has been rescinded at management request. Should the bureau be able to fill the position again, another announcement will be posted in due course.”

One person whose job offer was rescinded stated via Reddit: “Just signed a lease and I’m supposed to move across the country in three days. I’m feeling so panicked and confused. I really hope we at least get some guidance moving forward soon.”