Hong Kong (CNN)Philippine authorities on Monday launched a search mission atop a restive volcano after spotting the suspected wreckage of a missing plane carrying two Australians along with a Filipino pilot and crew member.
The six-seater Cessna 340 aircraft was bound for the capital Manila when it lost contact with air traffic control on Saturday after it left Bicol International Airport in Albay province, said the Civil Aviation Authority of the Philippines (CAAP).
The two Australians -- Simon Chipperfield and Karthi Santhanam -- were technical consultants working for Energy Development Corp., a Manila-based geothermal firm, the company confirmed in a statement.
"It's now the fourth day since they've gone missing, and considering the terrain and harsh weather, it's a difficult and challenging situation ... we continue to hope and pray that we will locate them," Allan Barcena, the company's assistant vice president and spokesman, told CNN on Tuesday.
In the statement, the company said its emergency response team had located wreckage at an altitude of about 6,000 feet (1,823 meters) near Mount Mayon, which last erupted in 2018, on Sunday.
Authorities were still working to reach the wreckage and verify it belongs to the missing plane, CAAP spokesperson Eric Apolonio told state broadcaster PTV on Monday.
"We only have aerial photos -- the drone shots -- but we cannot confirm if that is the said aircraft. Our accident investigators need to see the actual crash site on the ground," Apolonio said.
"We need to find the plane first before we can determine what caused the crash."
The wreckage is located near a "permanent danger site" and a determined "no-fly zone" around the volcano, and rescue teams have been given permission by the Philippine Institute of Volcanology and Seismology to begin the high-risk search operations, he said. Heavy rain and risk of landslides have added difficulty to the search.
More than 200 personnel along with 34 vehicles, 11 drones and four K9 dogs were deployed in the joint search and rescue operation to reach the aircraft in the remote volcano, according to state-run Philippine News Agency.
When Mount Mayon last erupted, it spewed ash and lava flow, forcing the evacuation of tens of thousands of villagers. The volcano's most devastating eruption took place in 1814 when at least 1,200 people were killed.
HK Yu, Australia's ambassador in the Philippines said on Twitter that the embassy is in contact with Philippine authorities and providing consular assistance to the families of the two Australians.
"Sadly, we are aware that two Australians were reported to be on the light aircraft which disappeared in Albay province in the Philippines on Saturday 18 Feb," Yu said. "Our thoughts are with the families, friends and loved ones of all those affected.