Racing resumed at Belmont Park in Elmont, N.Y., Wednesday for the first time since the deadly terrorist attacks of Sept. 11 that included the downing of the twin towers of the World Trade Center in nearby Manhattan after two hijacked planes rammed into them. A memorial service was conducted in the winner's circle at Belmont prior to Wednesday's 1 p.m. first post.Track announcer Tom Durkin called for a moment of silence that followed bugler Sam Grossman's playing of "America," while the American flag flew at half-mast in the track infield. At the end of the tribute a somber Durkin said simply, "God bless America. Thank you." A number of track officials, employees, and the New York jockey colony were among those attending the winner's circle ceremonies.Belmont last raced on Sunday, Sept. 9. In the wake of the attacks, track officials originally said they would reopen Belmont last Saturday, then decided to remain closed through the weekend. Belmont will be the site of the Breeders' Cup World Thoroughbred Championships on Oct. 27.Track officials said an early estimate for Wednesday's on-track attendance was 4,200, up marginally from the same day at Belmont Park in 2000.