All jockeys escaped serious injury after four horses were involved in a fall after the winning post in the fourth race at Ipswich.
Ipswich was rated in the good range in the morning but the race was run in driving rain and the meeting abandoned after 30mm fell in 30 minutes.
Steward Neil Boyle said Scott Galloway (Woolsey), Jackson Murphy (Gideons), Anthony Allen (Windchill) and Jake Bayliss (Phionax) were all dislodged.
He said the jockeys had all been checked by medical staff and cleared of any serious injury.
An inquiry has been opened into the fall.