F1 pre-season testing at the Bahrain International Circuit was interrupted after a pane of glass fell onto the track.
The glass window shattered on the start/finish straight, with marshals quickly arriving at the scene to sweep up the debris.
It is the second red flag for strange reasons halting running over the three-day test, after a circuit-wide power outage saw the afternoon session on day one extended by an hour to make up for lost time.
The glass fell from the box in which officials stand to wave the chequered flag.
However, in an apparent mix-up the green flag was shown after the glass was swept away. That lasted a matter of moments, before the red flag was thrown again.
But both Kimi Antonelli and Fernando Alonso emerged on track during the brief green flag interlude. The reason for the second red flag was a quad bike being on circuit.
