(10-23) 05:19 PDT SAN LEANDRO -- The driver of a paratransit van in San Leandro may have intentionally struck and killed a motorcyclist believed to be a member of the Hells Angels on Saturday in what is being investigated as a possible homicide, authorities said.

The crash happened when Eddie Hall, 31, of Oakland, the driver of an East Bay Paratransit van, crashed into the motorcyclist while both were traveling eastbound on Interstate 580 near the Grand Avenue on-ramp shortly before 4 p.m., said San Leandro police Sgt. Doug Calcagno.

The motorcyclist, an apparent member of the Hells Angels motorcycle club, was ejected from his bike and was then run over by the van, Calcagno said.

The van continued eastbound on the freeway, dragging the motorcycle until it pulled to the shoulder of the freeway near the 150th Avenue on-ramp, police said. The van came to a stop with the motorcycle still wedged underneath.

Hall tried to flee the scene of the crash but was detained and arrested on suspicion of felony hit-and-run, Calcagno said.

The victim was pronounced dead at Eden Medical Center in Castro Valley. His name was not immediately released. He was riding with Hells Angels members at the time of the crash, authorities said.

What led up to the fatality is still under investigation, Calcagno said. "We are unsure what caused this," he said, adding police are "attempting to determine if this collision was an intentional act or a accident."

The paratransit van was not carrying any passengers at the time, authorities said.

The collision closed all lanes on eastbound I-580 into late Saturday night, snarling traffic for miles. Shortly after the crash, the commute was brought to a standstill, and many motorists stood outside of their cars.

East Bay Paratransit is a public transit service for people who cannot use regular buses or trains because of a disability or health condition.