Two Kauai residents died on Sunday when a Civil Air Patrol plane crashed in the steep, mountainous terrain of Kauai’s Kalalau Valley, according to the Kauai Police Department.

The National Transportation Safety Board is investigating the Cessna 172 Skyhawk crash, which occurred about 3:15 p.m. during a regular monthly tsunami warning practice run.

First responders located the crash site on Sunday a few thousand feet below the first Kalalau Lookout in Kokee State Park. However, due to dangerous weather conditions and low visibility, rescue efforts were suspended Sunday evening.

A multi-agency rescue operation launched at first light on Monday morning. At approximately 10 a.m., police and fire officials recovered the bodies of the two pilots.

Kauai police identified the victims as James Degnan, 76, of Princeville, and David Parker, 78, of Kapaa.

Kauai County officials on Monday announced a “no fly zone” over Kokee State Park and Kalalau Valley, as well as the closure of the first Kalalau Lookout in Kokee due to the multi-agency recovery effort.

The scene of the crash has been turned over to the NTSB and the Federal Aviation Administration. An NTSB spokesman said the agency will publish a preliminary report on the crash in about two weeks.

The incident comes on the heels of another fatal airplane crash less than a month ago at Kauai’s Pacific Missile Range Facility.

Four people died on Feb. 22 when a military-contracted helicopter went down while offering retrieval support for a training operation. All four passengers were civilian employees.