A rescue team on Monday recovered the bodies of four people from the wreckage of a plane crash in rugged terrain around 100 kilometers (60 miles) south of Zagreb, Croatian civil defense officials said.

The Cessna aircraft disappeared from radar after taking off from the Adriatic coast city of Split on Sunday. It was heading to the western German city of Leverkusen where the pilot belonged to an aviation club. 

"As soon as the plane was spotted from above [by drone], search teams went to the scene," said civil defense director Damir Trut.

"Unfortunately, it has been confirmed that all the passengers have died," Trut told reporters. 

Hundreds of rescue personnel took part in the operation, which was complicated by rough weather and inaccessible mountainous terrain. 

What caused the crash?

Trut said authorities have launched an investigation into the accident. It has not yet been determined why the plane disappeared from radar and crashed. 

Croatian media reported that the weather in the area was bad and that the pilot sent an appeal for help, according to the Associated Press. 

The plane was returning to the Bayer Leverkusen Air Sports Club in western Germany when it crashed. 

The four people on board included two Germans, one Croat and one Swiss. The pilot and the other victims have not been immediately identified. The three passengers were acquaintances of the pilot.

The aviation club said the pilot was an experienced aviator and a "much appreciated, popular and dedicated member" of the club. 

"We have hoped and feared with the pilot's family, we have given each other courage and hope in the community of the air sports club," the club's chairperson Reinhard Sablowski said. "Now our worst fears have been confirmed," he added.

dh/wmr (dpa, Reuters, AP)