Police were looking for clues to an early morning shooting Sunday that seriously injured a 31-year-old man driving in Waialua.

The man’s condition improved to stable by Sunday afternoon, police said.

Police said the shooting occurred at about 4:30 a.m. in the general area of the old Waialua Sugar Mill camp.

The 31-year-old man was driving when someone shot a firearm toward his vehicle and struck him in the head, police said. Details on the caliber of the projectile and the exact area of the wound were unavailable.

Police said late Sunday afternoon that detectives had not yet been able to interview the victim. The case is classified as second-degree attempted murder.

Emergency Medical Services transported the man in serious condition to a hospital, EMS said in a report. Paramedics responded to an address on Haleki Street and treated the man at 4:43 a.m. for an apparent gunshot wound to the head.

Police confirmed the man drove to his home on Haleki Street after being shot.

A Dole Plantation security guard, parked on Haleki Street, said the area houses are home to retired plantation workers. Area residents said they knew nothing of the shooting.