LIHUE, Hawaii — Wildlife officials are still unsure what caused seven pilot whales to beach themselves along a Kauai beach.

The whales showed up at Kalapaki Beach last Friday. Of the seven, two died before they could be pushed back into the ocean. The other five went back into the water, but three more whale bodies later washed ashore.

Personnel from the University of Hawaii, NOAA Fisheries, Hawaii Department of Land and Natural Resources and volunteers worked together to conduct a necropsy, or post-mortem exam, on the five dead whales.

Preliminary results showed no obvious cause of death. Samples were taken and sent to labs for further analysis.

One thing they’re checking is to see if any of the rat poison dropped last month on Lehua Island made it into their systems. Results from those tests are not expected to be in for a while.

The Navy confirmed that there was no mid-frequency active sonar in the area at the time of the stranding. The Navy also confirmed there were no in-water explosives used in the area.

Officials ruled out the possibility of a ship spurring the whales to beach themselves. NOAA ship Okeanos Explorer was underway off Honolulu the day before the whales showed up. The ship’s seafloor imaging systems, however, including its multi-beam echosounder, were not in use during the ship’s safety inspection exercises.

No other NOAA ships were underway off Hawaii at the time.