A charred body was found inside the U.S. embassy in Belgrade, Serbia, after rioters stormed the complex Thursday evening in protest of Kosovo's declaration of independence, sources in Belgrade told FOX News.
The embassy gave a statement but wouldn't confirm the reports, which originated in the Serbian media.
"The security personnel are clearing the embassy as we speak … at this moment, they are unaware of any body being found in or outside of the embassy," the statement read. "They've gotten lots of calls about it, but cannot confirm it right now."
Angry demonstrators were still rioting well into the night. The mayhem came after a large organized protest against the situation in Kosovo.
Sources have provided conflicting reports on how extensive the breach of the U.S. Embassy was. Some told FOX News that no protesters made it into the building, which has been closed this week.
Other reports from The Associated Press noted masked attackers had gained entry and tried to throw furniture from an office. The reports also said a blaze had broken out inside one of the offices.
The neighboring Croatian Embassy also was attacked by the same group.
It took police about 45 minutes to appear at the scene, and firefighters arrived about the same time and put out the blaze. Police secured the U.S. Embassy and surrounding area, blocking off all access.
Crowds outside cheered and chanted. Riot police drove armored jeeps down the street and fired tear gas to clear the crowd.
In Washington, State Department spokesman Sean McCormack said the U.S. ambassador to Serbia was at his home and in contact with U.S. officials.
Security officials and Marine guards were in a different part of the compound, but nobody was inside the embassy building, he said.
"We want to strongly urge them, and we are in contact with them, to make sure that they devote the assets to deal with this situation," McCormack told reporters, referring to the Serbian government.
Serbia has "a responsibility now to devote the adequate resources to ensure that that facility is protected," McCormack said.
The U.S. Ambassador to the United Nations, Zalmay Khalilzad, said he was "outraged" by the attack and would ask the U.N. Security Council to issue a unanimous statement "expressing the council's outrage, condemning the attack, and also reminding the Serb government of its responsibility to protect diplomatic facilities."
Serbia's President Boris Tadic, on an official visit to Romania, appealed for calm and urged the protesters to stop the attacks and move away from the streets. Tadic said that violence was "damaging" Serbia's efforts to defend Kosovo, which declared its independence from Belgrade on Sunday.
The protesters appeared to have been in the Embassy's consular building area, McCormack said. U.S. security officials and Marine guards were in a separate part of the compound, the chancery, but no staff were present at the Embassy, he said.
More than a dozen nations have recognized Kosovo's declaration of independence on Sunday, including the United States, Britain, France and Germany.
But the declaration by Kosovo's ethnic Albanian leadership has been rejected by Serbia's government and the ethnic Serbians who populate northern Kosovo. Russia, China and numerous other nations have also condemned the declaration, saying it sets a precedent that separatist groups around the world will seek to emulate.
Elite police paramilitaries drove armored jeeps down the street outside the U.S. Embassy and fired dozens of tear gas canisters to clear crowds. The protesters fled into side streets where they continued clashing with the police.
Groups also broke into a McDonald's restaurant and demolished the interior. A number of other shops were also ransacked and people were seen carrying off running shoes, track suits and other sporting goods from a department store.
Doctors at Belgrade's emergency clinic reported treating more than 30 injured, half of whom were policemen. All were lightly injured, said Dusan Jovanovic, deputy chief of the clinic, adding that most of the injured protesters were "extremely drunk."
Kosovo, which is 90 percent ethnic Albanian, has not been under Belgrade's control since 1999, when NATO launched airstrikes to halt a Serbian crackdown on ethnic Albanian separatists. A U.N. mission has governed Kosovo since, with more than 16,000 NATO troops and KFOR, a multiethnic force, policing the province.
But Serbia — and Kosovo's Serbs, who make up less than 10 percent of Kosovo's population — refuse to give up Kosovo, a territory considered the ancient cradle of Serbs' state and religion.
For several days, Kosovo's Serbs have shown their anger by destroying U.N. and NATO property, setting off small bombs and staging noisy rallies.
Earlier Thursday, police estimated that about 150,000 people had attended a rally in the Serbian capital. The crowd waved Serbian flags and carried signs reading "Stop USA terror." One group set fire to a red-and-black Albanian flag.
On Thursday, the neighboring Croatian Embassy also was targeted by the same group of protesters at the U.S. Embassy, and smaller groups attacked police posts outside the Turkish and British embassies in another part of the city but were beaten back.
The Associated Press contributed to this report.