The 101st Indianapolis 500 has been red flagged after 55 laps following a huge crash between Jay Howard and Scott Dixon that has left debris strewn across the track.

Approaching the second round of pit stops, Howard ran wide and slammed into the wall before coming back across the circuit and careering into Dixon, who was unable to avoid his rival.

The force of the shunt sent Dixon's car into a roll before hitting the barrier violently and eventually coming to rest on the circuit.

Related Articles

Both drivers remarkably walked away unharmed, with Dixon jumping out of his car unaided despite only the survival cell on his Chip Ganassi Racing Dallara DW12 being intact.

Race officials were quick to red flag the race so that the debris on the track could be cleared, with Fernando Alonso being the incumbent leader.

After a poor start, Alonso picked his way from ninth to third through the opening stint before taking the lead on Lap 34 from Alexander Rossi.

Alonso and Rossi swapped the lead on a number of occasions as the second round of stops neared, with Alonso's advantage standing at 1.5 seconds before the red flag was thrown.