Donald Trump Jr. on Lewandowski Firing: 'Things Had to Change'

Donald Trump Jr. appeared on "Good Morning America" this morning.

"No, he didn't see this coming," he said of Lewandowski, adding that he wasn't physically escorted from the building. Trump Jr. said he was in the room when Lewandowski was fired. "There was nothing malicious or vicious about it."

A senior aide to the candidate told ABC News that Lewandowski's firing "was a long time coming" and that the campaign "need[ed] to get everyone on the same page."

Lewandowski told CNN Monday he didn’t know why he was fired.

"I don't know. I don't know the answer to that. But what I know is what we've been able to achieve in this election cycle has been historic," he said.

He also said that a man who allegedly tried to grab a police officer's gun last night to assassinate his father "of course" concerns Trump Jr., but he praised law enforcement and said, "You can only plan for so much."