ALGIERS, Algeria — “Are they dead? Did they attempt to flee the site after the attack like some other expatriates? Are they lost in the desert after taking a wrong turn?” an official who is part of Prime Minister Abdemalek Sellal’s office told The Associated Press. “These are all questions we ask ourselves, but one thing is sure, everything is being done to know their fate.”

The Ain Amenas gas plant, jointly run by BP, Norway’s Statoil and the Algerian state oil company, is located deep in the Sahara, some 800 miles south of the Mediterranean coast, with few population centers nearby.

More than 700 people work at the facility, including 130 foreigners from 26 countries who were targeted by the militants. The Islamists caught as many of those foreign workers as they could and wrapped some with explosives to use as human shields.

Many workers hid and then slipped out of the massive facility into the desert, eventually reaching the Algerian soldiers who had surrounded the complex.

A senior Algerian official said Tuesday that several Egyptian members of the squad of militants that laid siege to the gas complex last week also took part in the deadly attack on the U.S. mission in Libya in September.

The Egyptians involved in both attacks were killed by Algerian forces, the official said. But three of the militants were captured alive, and one of them described the Egyptians’ role in both assaults under interrogation by the Algerian security services, the official said.

If confirmed, the link between two of the most brazen assaults in recent memory would reinforce the transborder character of the jihadist groups now striking across the Sahara. U.S. officials have long warned that the region’s volatile mix of porous borders, turbulent states, weapons and ranks of fighters with similar ideologies creates a dangerous landscape of extremists trying to collaborate across vast distances.