LONDON (AP) -- One British and one Italian hostage held in Nigeria have been killed during a joint rescue operation, the U.K. prime minister said Thursday.
Chris McManus and Franco Lamolinara were captured in northern Nigeria in May. It appears that both hostages "were murdered by their captors before they could be rescued," British Prime Minister David Cameron said.
"The terrorists holding the two hostages made very clear threats to take their lives, including in a video that was posted on the Internet," Cameron said.
The U.K. leader said that after months of not knowing where the men were, British authorities had "received credible information about their location." Believing the men's lives were in "imminent and growing danger," Nigerian and British forces mounted a rescue operation.
It was not immediately clear when the men were killed. Cameron said "the early indications are clear that both men were murdered by their captors, before they could be rescued."
It appeared the operation may have taken place in Sokoto, a quiet city in Nigeria's northwest. An AP reporter there said the military surrounded a house in the city and there had been sounds of gunfire for much of the afternoon.
Gunfire continued into Thursday night as the military fought with those in Sokoto. An AP reporter there saw an ambulance ferrying the wounded, but could not get close to see who was inside. Security forces had a cordon up blocking journalists from getting within a kilometer of the site.
Police and local authorities in Sokoto have said the military operation in Sokoto was a hostage rescue, but they did not say who the operation was aimed at rescuing.
Italian Premier Mario Monti said Cameron had conveyed the news to him by telephone, saying in a statement that Nigerian and British authorities had determined the operation was the "last window of opportunity to save the hostages' lives."
The statement said the situation on the ground had accelerated recently, posing an "imminent danger to the lives of the hostages."
The Italians were only informed once the operation was under way, according to the statement.
Nigeria secret police spokeswoman Marilyn Ogar declined to immediately comment. An army spokesman could not be reached for comment.
A number of foreigners have been kidnapped while working in Nigeria in recent years. Many have worked in the oil industry.
Last year, the French news agency Agence France-Presse distributed a video of McManus and Lamolinara. The men appeared to be in good health despite months of captivity.
The kidnappers had claimed in the video they belonged to al-Qaida, something unusual in Nigeria, despite the presence in the country of a growing Islamic insurgent group known as Boko Haram.
U.K. officials had asked journalists not to publicize the video, in which the kidnappers threatened to kill the two men if their demands weren't met.
Associated Press writers John Gambrell in Lagos, and Nicole Winfield in Rome, contributed to this report.