The FBI said on Sunday it was investigating an incident in which a convoy of vehicles flying flags in support of President Donald Trump's re-election bid surrounded a tour bus carrying campaign staff for Democratic challenger Joe Biden on a Texas highway.
Friday's incident - captured on video that was retweeted by Trump on Saturday with the message, "I LOVE TEXAS! " - prompted the Biden campaign to cancel at least two of its Texas events as Democrats accused the president of encouraging supporters to engage in acts of intimidation.
Video footage showed a group of pickup trucks and SUVs bearing pro-Trump flags surrounding the Biden campaign bus as it traveled north along Interstate 35 between San Antonio and Austin.
The Biden campaign said the Trump caravan tried to force the bus to slow down and to run it off the road.
One video clip aired on CNN showed a Trump-flagged pickup swerve into the side of another vehicle traveling just behind the bus. The Texas Tribune newspaper reported the sideswiped vehicle was being driven by a Biden campaign staffer.
According to the Biden campaign, staff aboard the bus called emergency-911 to report the incident, with local law enforcement responding to the calls and assisting the bus reach its destination.