Three people were killed in the February 15 crash that prompted today's salvage operation.
It was unclear what caused the second crash, although an emergency-services source told Reuters that the aircraft crashed while trying to life the wreckage of the first helicopter.
Both helicopters -- which belonged to Iran's Oil Ministry -- crashed into Maharlou Lake, south of Shiraz.
Officials had blamed the earlier incident on a malfunction.
(Reuters, AFP)
