The 57th running of the Daytona 24 Hours has been red-flagged due to standing water on track with a little over seven hours left on the clock.
The field had been running under caution for more than an hour as marshals tried to clear standing water at the Bus Stop, following a shunt for Tommy Milner's Corvette at Turn 1 in the treacherous conditions.
Fernando Alonso led the field behind the safety car in the #10 Wayne Taylor Racing Cadillac DPi-V.R after surging to the front in the rain, with the two Acura ARX-05s of Dane Cameron and Ricky Taylor as well as the #31 Action Express Cadillac of Pipo Derani the only other cars still on the lead lap.
"Conditions are quite bad, now it's raining heavier," Alonso told NBCSN.
"For me, the visibility is OK, but if you are running fifth or sixth onwards the visibility will be a problem, and the aquaplaning.
"It's difficult to fix, now it's raining heavier. Let's see.
"As long as we are doing laps behind the safety car, it looked bad for the spectators, so it's better to stop and when the conditions are better let's go racing."
AXR pitted Derani shortly before the red flags flew without penalty.
The CORE autosport Nissan DPi completes the top five, four laps down on the lead with Colin Braun at the wheel.
LMP2 is led by the #81 DragonSpeed Oreca of James Allen by a lap over the sister car of Pastor Maldonado.
Six cars remain on the lead lap in GT Le Mans, with the #62 Risi Competizione Ferrari 488 GTE of Alessandro Pier Guidi heading the field ahead of the #912 Porsche 911 RSR (Laurens Vanthoor) and the #66 Ford GT (Joey Hand).
GT Daytona is led by the #86 Meyer Shank Racing Acura NSX with AJ Allmendinger at the wheel following a pitstop for the #33 Riley Motorsports Mercedes-AMG GT3, with Dries Vanthoor second in the Land Motorsport Audi R8 LMS.
The clock continues to run during the red flag period, with the race still due to conclude at 2:35pm local time (7:35pm UK time).
IMSA announced at 8:35am local time it would aim to restart the race at 9am (2pm UK time).