Experimental Plane Pilot and Fiancée Among 4 Dead in Crash Off California Coast

Wreckage of the plane crash was found near Moss Beach

An engaged couple is among the four victims who were killed in a plane crash near Moss Beach, off the California coast, on Sunday.

Australian Bay Area pilot Lochie Ferrier and fiancée Cassidy Petit of Hayward, California, were named by authorities on Tuesday, per NBC affiliate KNTV and 7News Australia.

The San Mateo County Coroner's Office identified a third victim, 27-year-old Emma Pearl Willmer-Shiles of San Francisco, on Wednesday, the outlets reported. Her body was recovered near the crash site on Monday.

A fourth victim is also believed to have been involved in the crash, the National Transportation Safety Board (NTSB) said, per CBS News.

Related: Woman’s Body Found After Small Plane Crashed into the Ocean Off California Coast

All four passengers were aboard a Cozy Mark IV, which was a four-seat homebuilt light aircraft, at the time of the accident, the FAA said, per ABC affiliate KGO-TV.

On Sunday evening, "authorities responded to reports of a small airplane flying erratically near Moss Beach," the San Mateo County Sheriff's Office (SMCSO) said in a press release posted to Facebook on Tuesday. The police added that "Witnesses observed the aircraft before it disappeared from sight."

The sheriff's office, California Highway Patrol and the U.S. Coast Guard all participated in a search for the aircraft when, "later in the evening, debris was found in the ocean near the coastline, consistent with parts from a plane."

The small plane was found upside down in the water near Ross Cove, authorities said, according to KGO-TV.

PEOPLE has reached out to the SMCSO and NTSB for further comment.

Couple Ferrier and Petit announced their engagement in a joint post on Instagram on Oct. 1, 2023. Petit’s last post to the platform was on Jan. 1. She shared a photo of her with Ferrier as she held up her engagement ring.

Ferrier was born in New South Wales and graduated in 2019 from Massachusetts Institute of Technology with a degree in aerospace engineering.

The pilot, whom 7News reported had a "love for experimental flight tests," recently joined the aviation and aerospace manufacturing company, Beta Technologies, as a team member in December 2023, according to his LinkedIn page.

Willmer-Shiles was also a student at Massachusetts Institute of Technology, graduating in 2018. She is believed to be Ferrier’s classmate, per CBS News.

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What caused the accident remains unclear at this time, CBS News reported.

According to the outlet and KNTV, the NTSB said the group's Cozy MK IV plane had initially departed from Hayward before landing in Half Moon Bay at 5:04 p.m on Sunday evening. The small aircraft then took off again around 7 p.m. and crashed minutes later, with wreckage found in the Moss Beach area.

An investigation into what caused the crash is ongoing. The local police "will continue to work collaboratively with the San Mateo County Coroner’s Office and NTSB to determine the cause of the crash and the circumstances surrounding the tragic event," SMCSO said.

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