A since-deleted statement released by the Vegas race on its social media platforms read: "Due to logistical considerations for our fans and our staff, we have made the determination that we will be closing all Las Vegas Grand Prix fan areas at 1.30am. We look forward to welcoming fans back later today for exciting FP3 and qualifying sessions".
Autosport understands that fans have had to leave the fan areas due to security team shifts ending, which means the grandstands and fan zones cannot operate as expected.
It is not currently clear why the statement was deleted from the Vegas race's social media accounts.
But the development means the FP2 session will therefore take place in front of empty grandstands and finish at 4am, the time the sections of track that take in public roads were supposed to be fully open to the public.
The heavily delayed timetable for the first day of F1 action in Las Vegas for 41 years was caused by the cancellation of the earlier FP1 session following Ferrari's Carlos Sainz and Alpine driver Esteban Ocon striking a loose water valve cover while traversing the lengthy Las Vegas Strip section of the 3.9-mile track.
Source: Autosport