"Luck" -- one of HBO's highest-profile series this season -- has been canceled after the death of a third horse during production.
A network spokeswoman said the show had "completed filming on episode one and was in production on episode two."
HBO gave no details on the accident, which happened at Santa Anita Racetrack in Arcadia, Calif., when a horse apparently reared up on its hind legs, then fell backward, striking its head.
It was euthanized shortly afterward, according to reports. During season one filming, in 2010 and 2011, two horses were hurt during racing scenes and euthanized.
After the third accident, producers said that pending an investigation, no horses would be used again during the production.
Instead, HBO pulled the plug.
While positively reviewed, the show -- which will wrap its first season in a couple of weeks -- has been lightly watched, with a recent episode drawing less than 700,000 viewers.
"Safety is always of paramount concern," the statement continued. "We maintained the highest safety standards throughout production, higher in fact than any protocols existing in horseracing anywhere with many fewer incidents than occur in racing or than befall horses normally in barns at night or pastures."
The network also released a statement from Mann and Milch, who said, "The two of us loved this series, loved the cast, crew and writers. This has been a tremendous collaboration and one that we plan to continue in the future."