General aviation pilot reported a vehicle crossed the runway as the pilot was rotating. With inadequate distance to stop; the pilot continued takeoff and flew over the vehicle.

Narrative

At approximately XA35 on Day 0 at ZZZ; I made a CTAF call on XXX.X that I was taking the runway XX for departure to the NE. I taxied my aircraft from taxiway 2 to line up on the numbers on the departure end. As I stopped; my instructor and I observed a group of ATVs or off-road vehicles along the edge of the runway in vicinity of taxiway 1. We recognized these vehicles as a group of personnel working to prepare the airport grounds for the upcoming airshow. The vehicles did not have flags. I only recall one of them had a flashing amber warning light. As we stopped on the runway; one of the vehicles crossed (left to right) in front of us. We paused our takeoff until we both confirmed the runway was clear. We saw one vehicle stopped on the right of the runway and 2 or 3 stopped on the left side. We assessed all stopped vehicles were at the distance they would be if they were behind the hold short line of taxiway 1 and runway XY/XX intersection. We did not hear any other radio communication from ground vehicles. With runway clear; I asked the instructor to 'keep an eye on them' and began my takeoff run. Power and engine gauges were normal. I made my airspeed callouts as normal. As I was confirming ROTATE speed; I observed one of the vehicles from the left of the runway begin to cross in front of us. With no time or space to stop; I proceeded with a normal takeoff; mindful not to over rotate. I estimate we cleared the vehicle that incurred the runway by 50-100 feet. We continued the flight with no other incidents. Prior to flight we conducted a full pre-flight brief to include weather and local NOTAMs. We noted the future NOTAM for ZZZ for the Airshow; but nothing active. After this incident; we verified again that the ZZZ airport NOTAM for runway XY/XX closure is not active until Day 7 at XA00 thru Day 19 at XF00.I have reason to believe the individuals on the ATV/off-road vehicles were volunteers and not familiar with proper airport operations and procedures and not actively monitoring or announcing their ground movements on CTAF. This could have been prevented if all personnel operating ground vehicles in the airport movement environment had proper markings and; for a pilot controlled airport such as ZZZ; actively monitor and announce their movements on CTAF.