The Transport Accident Investigation Commission has opened an inquiry into a skydiving crash at Lake Wakatipu, near Queenstown.
One of two men in a tandem jump remains missing after the pair plunged into the lake on Wednesday.
The commission says two investigators are due to arrive at the scene on Thursday.
It says the circumstances as reported are that, during a commercial tandem skydive, where the passenger is attached to an instructor, there was a possible malfunction of the parachute.
"The tandem master has been recovered from the lake and taken to Queenstown hospital with reported serious injuries," it said in a statement.
"The passenger is still missing."
The company involved in the jump, Queenstown-based NZONE Skydive, said it had suspended skydiving operations while the search for the missing man continues.
The company described the instructor as highly experienced and having completed thousands of jumps.
The accident happened near Jack's Point about 1.30pm.
The Coastguard, water taxis, helicopters and emergency staff went to the scene and WorkSafe were notified.
Police said a water and air search was suspended about 4.40pm, while a shoreline search involving LandSAR and the Coastguard was due to continue until 6.30pm.
All searching would be suspended overnight and police would asses the situation from 9am on Thursday.