Fairfax County police are searching for an unknown attacker who slashed three horses in a Herndon stable Wednesday night or Thursday morning.

The horses are expected to recover, but the bizarre attack — about 10 cuts in all — has spooked volunteers at the equestrian program for children with disabilities and left them wondering who would do such a thing.

“We’re all in shock. It’s a nightmare,” said Davorka Suvak, the program director of Spirit Open Equestrian Program. “It’s scary to know the type of person who could do this is running around in a park near kids.”

Spirit’s facility is adjacent to Frying Pan Farm Park in the 2600 block of Centreville Road. Police know of no motive and have no suspects in the cuttings, which they said occurred between 9 p.m. Wednesday and 9:30 a.m. Thursday.

Jeff Wallace, a Spirit volunteer, said he arrived on the scene shortly after 9:30 a.m. Thursday. He said that nothing was taken from the facility and that the program’s three other horses were untouched.

Spirit, a white pony, received at least six cuts on her hindquarters.

Suvak said Spirit might have walked up to the attacker because she is friendly and docile enough to be led by the small children the program serves.

Two other horses, Tessa and Lucinda, were also seriously wounded.

A veterinarian spent seven hours Thursday stitching up the cuts and giving the horses painkillers and antibiotics. Suvak said the veterinarian told her the length and depth of the wounds were consistent with a long, sharp knife. The veterinarian also told Suvak the cuts were fresh, so it is more likely the attack occurred Thursday morning.

A man was spotted stumbling in Frying Pan Farm Park about 11 a.m. Thursday, but it was unclear whether he is connected to the incident, police said.

Spirit’s facilities are “near a trail where a lot of local people go running. We’re hoping someone was on the trail and saw something,” said Officer Shelley Broderick, a spokeswoman for the Fairfax County police.

A security guard has been hired to keep an eye on the horses. Suvak said the program will also install video cameras at the stable. Her husband slept near the stable Thursday night to ensure the attacker did not return.

Spirit, a nonprofit organization founded in 2007, provides riding opportunities for people with physical, emotional and cognitive disabilities and diseases.

Suvak is staying positive, saying that donations have started flowing in and that parks officials have been helpful.

From the wounds on her leg, it appears that Tessa might have given the attacker a swift kick.

“We hope that she got him,” Suvak said.