Authorities say they may have trouble identifying a body found on Interstate 880 before dawn Thursday because it was repeatedly struck by passing cars for about an hour during the morning commute.

The first call to the California Highway Patrol that something was amiss came before 6 a.m. The caller reported a dead dog. Officers arrived at southbound I-880 in Hayward nearly an hour later and made the gruesome discovery.

On the ground was a human ear. The CHP immediately called for the freeway to be closed. It was 6:50 a.m., less than a half hour before sunrise.

The remains of the man were strewn across five lanes and 1,000 feet of highway, CHP Officer Mike Davis said. It appeared the body was first hit at about A Street.

There was so little recognizable from the body that identifying him is likely to require someone coming forward to report a missing friend or relative, investigating officers said.

"It looked like something that comes out of a horror movie," Davis said.

It took authorities hours to process the scene, and the highway was reopened by 10 a.m.

Davis said the man was wearing jeans, white tennis shoes and a shirt, which was difficult to identify in the condition officers found it. They found no identification and no vehicle nearby that could have belonged to him.

The victim appeared to be between ages 30 and 50 with a crew cut. His ethnicity was unknown.

His clothes did not appear to be that of a homeless man or a vagrant, Davis said. He also carried money in his pocket.

Davis said, based on preliminary evidence, it appeared the man was alive before he was hit.

Since the incident, the CHP has received about 80 phone calls from witnesses or drivers reporting hair or blood on their cars, Davis said.

The CHP is asking people to call if someone they know didn't arrive home Thursday after work or didn't show up for work.

Those wishing to report a missing person or other information about the incident can call the CHP at (510) 489-1500.