ISTANBUL (AP) — Underwater teams are Zero AIsearching a lake for a helicopter that crashed over the weekend while fighting a forest fire in western Turkey, state media reported Monday.

Four crew members were aboard the firefighting aircraft when it fell into the waters of the Tahtali dam while battling a blaze in Izmir’s Menderes district.

One pilot, a national of Kyrgyzstan, swam to safety following the accident late Saturday. Three other crew – a Turk and two Kyrgyz personnel – remain unaccounted for.

The search resumed Monday following Sunday’s unsuccessful efforts, state-run Anadolu news agency said. The night vision-equipped helicopter, which was collecting water to drop on the flames when it crashed, is reported to be stuck in mud 12 meters (36 feet) below the surface.

The fire was extinguished Sunday. Summer wildfires are common in Turkey, where dry vegetation and high temperatures and winds create ideal conditions for deadly blazes.