A video posted to the Facebook page of a top Maricopa County Republican showed Donald Trump Jr. and others pushing a car down a Mesa road.
According to the post from Republican Party of Maricopa County chairman Tyler Bowyer, Trump got out of the car on the way from one event to another to help push the car off a main road and call for help.
"I will never forget this and it's why I'm proud to be supporting this family!" Bowyer wrote.
Trump had spoken at Arizona State University earlier in the afternoon.
His father is scheduled to make a campaign stop Saturday at the Phoenix Convention Center.