OAKLAND --A crash involving a motorcyclist and a car on Interstate Highway 580 in Oakland temporarily blocked three lanes during this morning's commute, a California Highway Patrol officer said.Just after 8 a.m., a silver Mercedes and a motorcycle crashed on westbound Interstate Highway 580, just west of West MacArthur Boulevard, CHP Officer John Short said. A witness said it appeared several other vehicles might also have been involved. Short said an off-duty firefighter reported the crash and began assisting victims before emergency crews arrived. The motorcyclist, a female, is being taken to a hospital, CHP Officer Sam Morgan said. He did not know the extent of her injuries. Three lanes have been closed while the accident is cleared, Short said.