Donald Trump tore into a recent meeting between Bill Clinton and Attorney General Loretta Lynch Friday, telling a conservative crowd it had “opened up a Pandora’s box” and was "a very serious thing."

Speaking at the Western Conservative Summit in Denver, the presumptive Republican presidential nominee blasted the recent private meeting between the former president and Lynch aboard her plane at an Arizona airport.

Lynch has sought to temper the controversy over what she says is an impromptu meeting, admitting it “cast a shadow” over the public perception of her neutrality of the FBI-led probe into Hillary Clinton’s use of a private email server as secretary of state. Legal watchdogs have called the meeting highly improper and called for the Department of Justice’s Inspector General to investigate.

Trump mocked Lynch's claim that it was an impromptu meeting saying sarcastically, “he just happened to be there at that time." He was also skeptical about Lynch's claim that the pair just talked about golf and grandchildren.

"I love my grandchildren so much. But if I talk about ‘em for more than nine or ten seconds, where are we? I love my grandchildren. I love that one, I love that one, I love, love, love that one,” Trump said. “After that, what are you going to say? Right?”

However, he added that the situation was very serious.

Its not a joke, it’s a very serious thing,” Trump said, before calling Hillary “so guilty.”

“I think it really opened up a Pandora’s box, and shows what’s going on and shows what's happening with our laws and our government,” Trump said.

In the speech, Trump rallied his base with a speech that ranged from immigration to the economy. Both he and former Alaska Governor Sarah Palin sought to rally the base, with both giving optimistic presentations of the 2016 race.

“We’re doing great everywhere, much better than the press would have you believe,” Trump said.

“There are more of us than the disconnected left can even fathom,” Palin remarked, who also called Trump a “a golden wrecking ball” who broke down the walls of the “old boy’s club."

Outside, scenes turned ugly when a man grabbed pro-Trump bumper stickers from a woman outside the city's convention center, ripped them up and threw them in her face, The Associated Press reported.

A pushing match followed and people spilled into the street.

Police swarmed the crowd and ordered people to get out of the street. They led two men and a woman away, including the man who took the bumper stickers.

Some protesters sang "We Shall Overcome" and others waived the Mexican flag, saying "No justice, no peace."

Palin made reference to the protests in her speech, calling them paid protestors and joking: “Not even president yet and [Trump] is already creating jobs.”

The Associated Press contributed to this report.