The 28 passengers and crew of a ferry that ran aground off Kumano, Mie Prefecture, have all been rescued, the Japan Coast Guard said Friday.

The 7,910-ton Ariake was listing heavily when it ran aground, spilling oil over a wide area near the accident site.

The ferry, which left Tokyo on Thursday afternoon bound for Naha, Okinawa Prefecture, requested rescue at around 5:20 a.m. after rough waves apparently caused its load to shift, its Amami, Kagoshima Prefecture-based operator said.

The coast guard dispatched a helicopter and a patrol vessel to rescue the seven passengers and 21 crew members.

A 70-year-old passenger from Tokyo suffered bruises on his forehead and knee in the accident, while the 42-year-old chief engineer hurt his shoulder. Their injuries are not serious, rescue personnel said.

The passengers said they were frightened.

"I was awakened by a loud noise but couldn't even stand up," one said. "It scared the hell out of me."

The transportation safety board dispatched four inspectors to Mie Prefecture to investigate the cause of the accident, while the local coast guard opened an investigation on suspicion of obstructing navigation.