“We must assume that they were kidnapped,” a spokesperson said, adding that an emergency task force was working to find a quick solution to the situation.

The vacationers were abducted along with five Italians and a Romanian tourist in a remote desert in southwestern Egypt on Friday, an Egyptian security official told state television on Monday.

The group was on a safari in the Sahara Desert near Kark-Talh when their vehicles were stopped by masked men with weapons and taken towards Sudan, according to Egyptian sources. The kidnappers are demanding $15 million for the release of the hostages, news agency DDP reported, a figure the German Foreign Office has not yet confirmed.

“Four masked gunmen attacked the four cars they were riding and led them towards Sudanese territory at gunpoint,” the state MENA news agency quoted an unnamed official as saying.

The tourism ministry said the kidnapping happened on Friday but authorities only became aware when the tour company owner, who is among the missing, used a satellite telephone to call his German wife and tell her of the ransom demand.