EMERYVILLE -- Police are investigating a body discovered Wednesday morning below an overpass near the West MacArthur Boulevard ramps from Interstate 580.

A man's body was reported around 5:30 a.m. under the overpass at Emery Street and West MacArthur. The man was white and believed to be in his 40s, Emeryville police Officer Brian Head said.

The coroner arrived on the scene about 6:30 a.m.

The man had not been identified by late Wednesday. Head said an autopsy was scheduled on Thursday with the Alameda County Coroner's Office.

"We don't know yet if this is a crime or an accident," Head said. "It's also not clear yet if he died from a fall or if he was down there and was struck by a vehicle."

Both the on- and off-ramps to the freeway have reopened, officials said.

Contact Sean Maher at 925-943-8013. Follow him at Twitter.com/OneSeanMaher.