SACRAMENTO, Calif. (AP) — Police on the hunt for a gunman shut down a busy stretch of Interstate 80 in Northern California on Friday as officers scoured a vast flood control basin beneath the freeway and nearby neighborhoods.Authorities believe the gunman opened fire at a commercial trucking business in West Sacramento and crashed a stolen getaway vehicle during a police chase.No one was injured, but officers closed a stretch of the highway on the three-mile-long elevated Yolo Causeway as they searched for a man they said was wearing a long trench coat-style jacket.About 4-1/2 hours after the closure, there were reports of another carjacking in West Sacramento. Police were searching for a brown Ford F-150 pickup truck and say the suspect may be the same person they were seeking.