"These accidents have hit us hard in the sport of eventing," said the body's president, David O'Connor, and US Eventing Association president Kevin Baumgardner in a joint statement.
"We are all riders who care deeply about the horses, their welfare and the image of the sport," the pair said in announcing a USEF/USEA Safety Summit to be held in Lexington, Kentucky, on June 7-8.
"We are working closely with FEI to do whatever we can to better protect riders and horses and to repair the public image of our sport," they said. Both acknowledged that more needed to be done to improve safety.
Last weekend at the Rolex Kentucky Three-Day, Laine Ashker, 25, suffered a serious fall during the cross-country stage of the competition. She is in critical condition at the University of Kentucky hospital in Lexington. Her horse and another involved in a separate accident had to be euthanized.
The accidents come just a month after Olympic rider Darren Chiacchia fell at an event in Florida. They also come after a recent article in The New York Times about 15 rider fatalities in cross-country events worldwide in the last two years.
"This spate of accidents has raised important and potentially troubling questions for those of us who govern the sport," O'Connor and Baumgardner said.
"Why are so many riders and horses having accidents? Is there more that can be done to make cross country safer? Is the sport just too dangerous?
"There is no question that eventing is a demanding and yes, risky sport. Riders cross undulating terrain at high speed and jump a series of challenging fences - all while atop a 1000-pound horse. There is a constant need for us to ensure that every precaution is being taken to reduce the risk of injury to riders and horses."
The pair said that although several measure have been implemented to improve safety in the last year, clearly more needed to be done.
"In the coming days and weeks, we will be redoubling our efforts to identify additional steps we can take to make sure that riders and horses can compete as safely as possible. We would like to ask your help in this effort - whether you're a rider, trainer, coach, veterinarian, or simply a horse enthusiast."
The safety summit, they said, would be open to all and would break the issue of safety down to examine the causes and potential solutions.
"Over the last few days, we have received emails from people who were at the Rolex event over the weekend and were disturbed by what they saw. They are asking hard questions of us and questioning whether they should continue to support the sport of eventing.
"To them and to you, we want to say that we too are disturbed by what we see. No matter how much we tell ourselves that injury is a part of our sport, it is always traumatizing to see a horse fall.
"We are proposing today that within the United States the following five initiatives be put into effect: