Date: 201910
Local time of day: 0001-0600
Location: DFW.Airport, US
Flight conditions: VMC
Aircraft: Medium Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class B DFW
ATC / advisory: Tower DFW
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Distraction; Communication Breakdown
Second reporter function: Captain; Pilot Flying
Anomaly: Ground Event / Encounter Vehicle; Ground Incursion Runway
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Contributing factors: Airport
Primary problem: Airport

Narrative: We were cleared for takeoff on Runway 36R. We had a 22K Wet TPS (Takeoff Performance System) for the runway. Somewhere around 140 kts.; I noticed flashing red lights approaching the departure end of the runway from the west; in the vicinity of Taxiway Y; and they were approaching at a high rate of speed. The Captain asked; 'Is he crossing?!' I said; 'I think so!' As the vehicle entered the runway; he turned the flashing red lights off. Once on the other side; he turned them on again. We elected to continue the takeoff roll as we were above V1 and approaching VR. We rotated at VR and lifted off somewhere around the middle of the B Terminal normally.Once airborne; with the gear selected up; I queried Tower and asked if a vehicle crossed the runway in front us on takeoff. The Controller sounded shocked and then asked if there were any Port Vehicles on frequency. He then told us he didn't see anything; but said he would pass a phone number to Departure and asked us to call them when we landed. He then switched us to Departure. At that point; both the Captain and I appeared a bit rattled. We continued the clean-up at a much slower and methodical pace; considering what just happened. On climb out; we discussed the event and how it shook both of us. We slowed down and took our time to get ourselves back into the green and continued to ZZZ normally. The driver appeared to willfully violate the rules and entered the runway as we were on the takeoff roll. The driver needs to be retrained.


Second narrative: Runway 36R at DFW. 24K thrust flap1 wet TPS. During the takeoff run approximately 2-3 kts. below V1; [we] observed a truck on the west side of the runway; appearing to be in the area of taxiways Z and Y. The truck had red flashing lights on top of the truck and they were on. The truck entered the runway [and] at about the midpoint of the runway; the red flashing lights went off. The truck continued across the runway. Exiting the runway on the east side; the red flashing lights were turned on again. [I] made a comment to the First Officer. Something like; 'Is he crossing?' or something similar. I remember he replied in a very surprised way; 'Yes.' I took a quick look at the airspeed; saw we were just a kt. or 2 below Vr and we continued the takeoff. Truck driver error? I could not really explain why. More awareness of location on airport by service vehicles.


Synopsis: Air carrier flight crew reported an unknown vehicle crossed the runway as the aircraft reached rotation speed.