ALGIERS/BAMAKO/PARIS: More than 20 foreigners were still either being held hostage or missing inside a gas plant Friday after Algerian forces stormed the desert complex to free hundreds of captives taken by Islamist militants.

More than a day after the Algerian army launched an assault to seize the remote desert compound, much was still unclear about the number and fate of the victims, leaving countries with citizens in harm’s way struggling to find hard information.

Reports on the number of hostages killed ranged from 12 to 30, with anywhere from several dozens to scores of foreigners still unaccounted for.

An Algerian security source said 30 hostages, including at least seven Westerners, had been killed during Thursday’s assault, along with at least 18 of their captors. Eight of the dead hostages were Algerian, with the nationalities of the rest of the dead still unclear, he said.

A local Algerian source said 100 of 132 foreign hostages had been freed from the facility. However, other estimates of the number of unaccounted-for foreigners were higher. Earlier the same source said 60 were still missing. Some may be held hostage; others may still be hiding in the sprawling compound.

U.S. officials said one of the American hostages, a Texas resident, Frederick Buttaccio, had died.

The French foreign minister also said Friday evening that a Frenchman had been killed while three others were saved when the Algerian army stormed the gas plant.

“The Algerian authorities have just informed us that one of our compatriots, Mr. Yann Desjeux, unfortunately lost his life during the operation to free hostages,” Laurent Fabius said.

“The lives of three others of our compatriots who were on the site during the terrorist attack have been saved,” he added.

Algeria’s state news agency APS put the total number of dead hostages at 12, including both foreigners and locals.

Leaders of Britain, Japan and other countries expressed frustration that the assault had been ordered without consultation. Many countries were also withholding information about their citizens to avoid helping the captors.

U.S. Secretary of State Hillary Clinton told Algeria to do everything possible to protect hostages as it sought to free them.

Clinton said that in her conversation Friday with Algerian Prime Minister Abdelmalek Sellal, she had underscored that “the utmost care must be taken to preserve innocent life.”

The State Department said Americans were still being held hostage, and world leaders have criticized Algeria for its handling of the attack.

Clinton did not criticize the North African country.

The attack, she said, was an “act of terror.” She also vowed greater U.S.-Algerian counterterrorism cooperation in future.

The attack has plunged international capitals into crisis mode and is a serious escalation of unrest in northwestern Africa, where French forces have been in Mali since last week fighting an Islamist takeover of Timbuktu and other towns.

“We are still dealing with a fluid and dangerous situation where a part of the terrorist threat has been eliminated in one part of the site, but there still remains a threat in another part,” British Prime Minister David Cameron told his parliament.

Norway’s Prime Minister Jens Stoltenberg, eight of whose countrymen were missing, said fighters still controlled the gas treatment plant itself, while Algerian forces now held the nearby residential compound that housed hundreds of workers.

Stoltenberg said some of those killed in vehicles blasted by the army could not be identified. “We must be prepared for bad news this weekend but we still have hope.”

Northern Irish engineer Stephen McFaul, who survived, said he saw four trucks full of hostages blown up by Algerian troops. Two Japanese, two Britons and a French national were among the seven foreigners confirmed dead in the army’s storming, the Algerian security source told Reuters. One British citizen was killed when the gunmen seized the hostages Wednesday.

Those still unaccounted for Friday included 10 from Japan and eight Norwegians, according to their employers, and a number of Britons which Cameron put at “significantly” less than 30.

The attackers had initially claimed to be holding 41 Western hostages. Some Westerners were able to evade capture by hiding.

They lived among hundreds of Algerian employees on the compound. The state news agency said the army had rescued 650 hostages in total, 573 of whom were Algerians.

Meanwhile, Islamist rebels in Mali abandoned the central town of Diabaly Friday after fleeing a French airstrike, military sources said, while West African troops arrived in Bamako to take on the insurgents in Mali’s north.

France, warning that Islamist control over Mali’s vast deserts and rugged mountains threatened the security of Africa and the West, had targeted Diabaly in an eighth day of airstrikes to dislodge hardened Al-Qaeda-linked fighters there.

“They [the Islamists] fled the town, dressed as civilians, early this morning. They abandoned their weapons and ammunition,” a Malian military source said.

The source added that government soldiers had not yet entered the town but Diabaly Mayor Oumar Diakite told Reuters that troops were there carrying out mopping-up operations after a French airstrike earlier in the day.

Diakite said residents had dug up some of the Islamist fighters’ weapons caches. “There are lots of burned-out vehicles that the Islamists tried to hide in the orchards,” he added.