The St Petersburg IndyCar race has been red-flagged on Lap 1 after an ugly pile-up.

The drama began when Scott Dixon (Chip Ganassi Racing) and Felix Rosenqvist made side-to-side contact as they approached Turn 3, causing the latter to glance the wall.

The McLaren driver slowed as a result, which bottled up the back of the pack and set off mayhem.

Meyer Shank Racing team-mates Helio Castroneves and Simon Pagenaud were already involved in the crash when Benjamin Pedersen (AJ Foyt Racing) t-boned a stricken Devlin DeFrancesco, causing the #29 Andretti Autosport entry to get airborne.

Sting Ray Robb (Dale Coyne Racing w/ RWR) was also caught up in the drama.

The #FirestoneGP is red flagged after this lap 1 incident.#INDYCAR // @GPSTPETE pic.twitter.com/7s50XtKiTi

— NTT INDYCAR SERIES (@IndyCar) March 5, 2023

Castroneves, Pagenaud, Pedersen, and DeFrancesco were able to exit their vehicles under their own power, the former with something of a limp, and Robb drove back to the pits.

DeFrancesco has since already been cleared and left the medical centre.

Both AJ Foyt cars were in fact taken out by the incident, with Santino Ferrucci walking away from the #14 Chevrolet after stopping in the Turn 4 run-off area.

Romain Grosjean had converted pole position into the race lead, with his Andretti Autosport team-mate Colton Herta holding off McLaren’s Pato O’Ward for second place.

Australian viewers can watch live and ad-free on Stan Sport.

Update 05:11 AEDT

Race restarted; Grosjean leads after 15 laps.

CLICK HERE for race report