MIAMI (AP) _ A Venezuela-bound Pan Am flight buffeted by severe turbulence that injured 30 people resumed Thursday with all but four of the passengers aboard.

The A-310 Airbus was over the Atlantic on Wednesday when it suddenly dipped and lurched, tossing many of the 127 passengers and nine crew members around the cabin like rag dolls.

''It was clear air turbulence,'' Pan Am spokeswoman Pamela Hanlon said Thursday. ''The flight was cruising at 33,000 feet, and there was absolutely no warning.''

The plane, en route from New York to Caracas, Venezuela, and then Trinidad, made an unscheduled landing at Miami International Airport where paramedics treated the injured and routed them to hospitals. Injuries ranged from cuts to broken bones.

Two people remained hospitalized Thursday, said Baptist Hospital spokeswoman Adrienne Sylver.

She identified them as Henry Hazzard, 60, of Roosevelt, N.Y., who had cardiac problems, and Erch Gonda, 46, of Dusseldorf, West Germany, who suffered bumps and bruises. Both were in satisfactory condition and were expected to be released shortly, she said.

Two other passengers elected to remain in Miami temporarily, said Ms. Hanlon. The rest left Miami on a special Pan Am flight Thursday afternoon, said Alan Loflin, spokesman for Pan Am.

The interior of the plane shaken by the turbulence was slightly damaged, but the aircraft was sound and was expected to be back in service within a day, Ms. Hanlon said.

The unexpected winds hit about 340 miles northeast of Miami as passengers waited for the in-flight movie ''The Untouchables'' to begin, said Loflin.

Clear air turbulance cannot be detected by sky conditions or radar and affects a plane like the cracking of a whip, federal officials said.

''It just happens seriously two or three times a year, and there's absolutely nothing you can do to prevent it,'' Loflin said.

Passenger Omah Singh, who had a bandage on his head, said in the terminal after the plane landed that the turbulance ''was a total shock.''

''I just kept bouncing back and forth. ... I thought I was going to die,'' he said.

U.S. Rep. Bruce Morrison, D-Conn., also a passenger on the flight, said, ''We just hit an air pocket and the plane fell. It happened twice in a row.''

He added, ''It's a good lesson for people about why they tell you to keep your seatbelt fastened in the air.''