The Formula 3 sprint race at Monaco was red-flagged after a multi-car collision at the Fairmont hairpin on the opening lap blocked the track and brought the field to a halt.
The incident occurred during the first race of the weekend in Monte Carlo, at the
slowest corner on the Formula 1 calendar, where the tightly packed field concertinaed shortly after the start of the 23-lap race on Saturday.
MP Motorsport's Tuukka Taponen appeared to trigger the chain reaction, with Brad Benavides of AIX Racing, Rodin Motorsport's Brando Badoer and team mate Christian Ho among the drivers caught up in the incident. Benavides was hospitalised.
Monaco's narrow layout and lack of escape roads left several cars stranded at the hairpin, forcing race control to suspend proceedings almost immediately and display the red flag on lap one.
Initial television images suggested all involved drivers were able to exit their cars, although attention quickly turned to Benavides as officials awaited confirmation of his condition. Early reports indicated there were no serious injuries.
The stoppage was the latest incident in an eventful Formula 3 weekend around the streets of Monte Carlo.
Thursday's practice session was interrupted by a heavy crash for PREMA driver James Wharton at the Swimming Pool section after an apparent steering failure. The Australian walked away unhurt, but barrier repairs forced an extension to the session.
Campos Racing's Théophile Naël emerged as the pace-setter in practice before securing pole position for Sunday's feature race during Friday's split-group qualifying session.
The sprint race grid had been formed using Formula 3's reverse-grid format, with the top 12 qualifiers reversed and Japan's Hiyu Yamakoshi starting from pole position.
Further updates on the sprint race result, potential penalties and the condition of those involved were expected from FIA Formula 3 officials following the restart or conclusion of the event.
Formula 1 FP3 and Qualifying will take place later in the day, as well as the Formula 2 sprint race.