Update:FBI San Antonio confirmed to KSAT 12 Sunday afternoon that it is investigating the incident involving a group of Trump supporters surrounding and following a Biden campaign bus as it drove up I-35 in Hays County. According to the Biden campaign, multiple trucks pulled in front of the bus and appeared to try to slow it down. "All involved parties are being referred to the San Marcos Police Department should they desire to file any type of report with law enforcement. Democratic officials say Trump supporters created a dangerous situation on Interstate 35 and continued following the bus into Austin. Sorry to all who looked forward to this fun event.”RELATED: Biden camp cancels multiple Texas events after a “Trump Train” surrounded a campaign bus