BAMAKO, Mali — Without warning other governments, Algeria mounted an assault Thursday on the heavily armed fighters holding American and other hostages at a remote Sahara gas field facility, freeing captives and killing kidnappers but also leaving some of the hostages dead and foreign leaders scrambling to find out the fates of citizens trapped inside.
Hours after the raid, there was still no official word on the number of hostages who were freed, killed, or still held captive. Estimates of the foreign casualties ranged from four to 35, though one Algerian official said the high figure was ‘‘exaggerated.’’
Despite requests for communication and pleas to consider the safety of their abducted citizens, the United States, Britain, and Japan said they had not been told in advance about the military assault, stirring frustration that the Algerians may have been overly aggressive and caused needless casualties.
But the Algerian government, which has a history of violent suppression of Islamist militancy, stood by its decision to deal forcefully with the kidnappers.
‘‘Those who think we will negotiate with terrorists are delusional,’’ the communications minister, Mohand Said Oublaid, said in an announcement about the assault on the facility near In Amenas, in eastern Algeria, close to the Libyan border. ‘‘Those who think we will surrender to their blackmail are delusional.’’
The midday assault came more than 24 hours after a militant group, which the Algerians said had ties to jihadis in the region, ambushed a bus carrying gas field workers to a nearby airport and then commandeered the compound.
It was one of the boldest abductions of foreign workers in years.
After the raid to free the hostages, the Algerians acknowledged a price had been paid.
‘‘The operation resulted in the neutralization of a large number of terrorists and the liberation of a considerable number of hostages,’’ Oublaid said. ‘‘Unfortunately, we deplore also the death of some, as well as some who were wounded.’’
Algerian national radio described a scene of pandemonium and high alert at the public hospital in the town of In Amenas, where wounded and escaped hostages were sent.
The director of the hospital, Dr. Shahir Moneir, said in the report that wounded foreign hostages were transferred to the capital, Algiers.
In a telephone interview from the hospital, one of the Algerians held captive, who identified himself as Mohamed Elias, said some of the hostages had exploited the chaos created by the Algerian military assault to flee.
‘‘We used the opportunity,’’ he said, ‘‘and we just escaped.’’
Senior US military officials said that aides traveling in London with Defense Secretary Leon E. Panetta were struggling to get basic information about the raid, and that an unarmed US Predator drone was monitoring the gas field site.
The senior official said that possibly seven to eight Americans were among the hostages — the first official indication of the number of Americans involved — and that he did not know if any had been killed in the raid.
Prime Minister David Cameron of Britain said his office had not been told ahead of time, an implicit criticism of the Algerian government.
A spokesman said Cameron had learned of the raid through Britain’s own intelligence sources and that ‘‘the Algerians are aware that we would have preferred to have been consulted in advance.’’
A European diplomat involved in the effort to coordinate a Western response to the hostage seizure said the information available to the United States, France, and Britain had been ‘‘confusing at best, and sometimes contradictory.’’
Several Western officials complained that the Algerians appeared to have taken none of the usual care exercised when trying to free hostages with minimal casualties.
Even before reports of the Algerian military’s raid began to emerge, many hostages — Algerian and foreign — were reported to have escaped as the kidnappers failed to persuade Algerian authorities to give them safe passage with their captives. The Algerian news site TSA quoted a local official, Sidi Knaoui, as saying that 10 foreigners and 40 Algerians had managed to flee after the kidnappers had made several efforts to leave with their captives.