Story highlights The two men died Saturday in San Joaquin County

Preliminary investigation indicates the parachute did not open

(CNN) Two skydivers died after their parachute apparently failed to open following a tandem jump in Northern California, authorities said.

The men, who are in their 20s, died Saturday in San Joaquin County. They have not been identified.

Authorities received a call that the skydivers had hit the ground without an open parachute, said Lt. Randy Johnson of San Joaquin Sheriff's Office.

A preliminary investigation indicates the parachute did not open, Johnson said. Their bodies were found in a vineyard in the Lodi area.

Bill Dause, owner of the Lodi Parachute Center where the two jumped from, told CNN affiliate KCRA that one of the victims was an instructor with 700 jumps of experience.

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