(NewsNation) — Whistleblower David Grusch is not the only high-level government official to come forward with claims about UFOs, according to Sen. Marco Rubio, R-Fla.

Rubio told NewsNation on Monday that he has heard from firsthand witnesses in “high positions in our government” to some of the claims made by Grusch.

“There are people that have come forward to share information with our committee over the last couple of years. … I want to be very protective of these people. A lot of these people came to us even before protections were in the law for whistleblowers to come forward,” Rubio told NewsNation’s Joe Khalil during an exclusive interview.

Grusch claims the government is covering up evidence that UFOs really are extraterrestrial and that he has seen evidence of a secret crash retrieval program. The Air Force veteran alleges the U.S. has even retrieved bodies from other species. Grusch spoke about these claims exclusively to award-winning investigative journalist Ross Coulthart, reporting for NewsNation.

Rubio said that some of the officials with similar claims to Grusch are public figures with “high clearances.”

“We’re trying to gather as much of that information as we can … And frankly, a lot of them are very fearful of their jobs … fearful of harm coming to them,” Rubio added.

Rubio did not comment on if he thinks the claims are credible, but he said he doesn’t see a reason why those who have come forward would lie.

“What I think we owe is just a mature, you know, understanding, listening and trying to put all these pieces together and just sort of intake the information without any prejudgment or jumping to any conclusions,” Rubio said.

UFO expert Nick Pope told NewsNation that based on Rubio’s statement, more individuals will come forward.

“There’s safety in numbers,” Pope said. “People are cautious about this, but once the first few speak out, I think others come forward.”