A pilot and his passenger died Monday afternoon when their single-engine, homebuilt aircraft crashed into a marshy area near La Center, Washington.

The Clark County Sheriff’s Office said another pilot flying overhead spotted the downed propeller aircraft shortly after 4 p.m., south of the East Fork of the Lewis River. Emergency responders found the plane in a pond about two-feet deep.

The National Transportation Safety Board described the plane as a Vans RV-6, a small plane built from a kit.

The occupants of the two-seater plane, both adult males, were dead when emergency responders arrived and appeared to have died on impact. The sheriff’s office said the plane was registered in Clark County but that it hasn’t identified the crash victims.

The plane crashed near Daybreak Airport, according to the sheriff’s office. That’s about 20 miles north of downtown Vancouver.

The sheriff’s office said it’s unclear what caused the crash. Local authorities are awaiting investigators from the Federal Aviation Administration.

-- Mike Rogoway | twitter: @rogoway | 503-294-7699