The search is on for three European tourists lost on a Chilean volcano

Three days of searching has found no trace of three European tourists who went missing while hiking at one of this South American nation's most active volcanos, authorities said Saturday.

Teams led by special police and the Andean Aid Team have been sweeping the area around the Villarica volcano in Chile's central valley since Thursday morning.

The missing Europeans are identified as Dmitry Sivenkov, 32, of Russia; Gillhem Bellon, 25, of France; and Luca Ogliengo, 25, of Italy. Ogliengo's family has rented a private helicopter to join the search.

The hikers haven't been heard from since around 7 p.m. Wednesday, when one of them called his girlfriend who lives in the nearby community of Pucon, authorities said. He told her it was getting late and dark so the group decided to sleep over at the volcano and descend the next day.

"What worries us is that they were unprepared to sleep over in the volcano," the director of the regional emergency office, Janet Medrano, told The Associated Press.

"They were there only for a day hike and that night a cold front cooled temperatures and brought a lot of snow, which could have covered their footprints," Medrano said.

The search began early Thursday after the snowy weather cleared out.

"Unfortunately, after three days there's no trace of these persons," Medrano said.

She said Saturday's search began at 6 a.m. and ended at 6 p.m. because of darkness. She said the teams would be back out searching on Sunday.