Flight attendants clearing meals in a United Airlines cabin slammed into the plane's ceiling early Thursday when their flight from Maui, Hawaii, to San Francisco dropped sharply as it passed near a storm front.
Ten people -- including five of the 147 passengers -- were injured, seven badly enough to go to the hospital, according to San Francisco International Airport officials.
The seat belt sign was on when the plane began to shake and suddenly plunged toward the Pacific about an hour southwest of San Francisco, according to the airport duty manager, Dennis Neves.
"Once you've got a sharp drop like that, everything hits the roof," he said.
When the flight arrived about 4:30 a.m., paramedics treated 10 people at the gate.
Four of them had their necks and backs stabilized before being taken to the hospital. Neves said he thought the plane was flying close to a storm that was bearing down on San Francisco.
A National Weather Service meteorologist said the plane was probably near the storm front and jet stream when it hit turbulence.
The storm is expected to drop several inches of rain on Northern California, starting Thursday.