This bay stallion, known as Sir Gruff, was killed at Assateague Island National Seashore in a collision with a vehicle/NPS

An investigation was underway at Assateague Island National Seashore on the Virginia-Maryland coast where an 18-year-old bay stallion was struck and killed by a vehicle on Maryland 611.

The highway, which accesses the seashore via a causeway, has proven dangerous for motorists and horses through the years. Since 1982 19 horses have been killed in collisions, and another six have been injured. The latest casualty was known as N9BFNY, aka Sir Gruff. He was killed Tuesday evening around 7:30 p.m., a park release said. It was not immediately known if speed was a factor.

Sir Gruff and his band, N10T (Ninka) and N10T-JO (Assateague Phoenix) normally range in the vicinity of Tingles Island and Pine Tree backcountry sites, but they have spent the summer in the developed area, the seashore said.