California Highway Patrol said the incident happened along Interstate 80, but the agency could not confirm if it was a freeway shooting, or police pursuit.
Traffic in the area was heavy as police conduct an investigation on the freeway.
A 2-year-old thoroughbred colt died during a training session at Golden Gate Fields in Berkeley on Monday, the California Horse Racing Board reported.
The $18.9 million East Bay Regional Park District project added a new mile-long segment to the trail behind the Golden Gate Fields racetrack, closing a gap in the trail between Berkeley and Albany.
Also victim of the health restrictions is the city's biennial Dinner with Albany, an outdoor dining gala held on Solano Avenue.
The death of Arky Vaughan, a 3-year-old gelding, was the 10th horse race death at Golden Gate Fields and the 38th in California so far this year, according to activist Heather Wilson, who is based in the Los Angeles area.
The Gelding is the tenth to die at Golden Gate Fields this year.