By Mohammed Ghobari
SANAA (Reuters) - Hundreds of Yemeni demonstrators stormed the U.S. embassy compound in Sanaa on Thursday in protest at a film they consider blasphemous to Islam, and clashes with security forces killed at least one person and injured 15 others.
Young protesters, shouting "We sacrifice ourselves for you, Messenger of God", smashed windows of the security offices outside the embassy with stones and burned at least five cars as they broke through the main gate of the heavily fortified compound in eastern Sanaa, the witnesses said.
"We can see a fire inside the compound and security forces are firing in the air. The demonstrators are fleeing and then charging back," one witness told Reuters.
Witnesses said embassy guards fired in the air to keep the protesters at bay. Riot control forces later used tear gas and water cannon to disperse the demonstrators.
A local hospital official said the body of one person had been brought in from the scene of the clashes and medics were trying to determine the cause of death. A security source said at least 15 people were wounded, some from bullets and 12 people were arrested.
"All embassy personnel are safe and accounted for," an embassy spokesman told Reuters by telephone.
The protest followed Tuesday night's storming of the United States Consulate and a safe house in Benghazi, where the U.S. ambassador to Libya and three other staff were killed. President Barack Obama said the perpetrators would be tracked down and ordered two destroyers to the Libyan coast.
Protesters also attacked the U.S. embassy in Egypt and there were fears demonstrations would spread to other countries in the Muslim world.
Demonstrators blamed the United States for the film, posted on YouTube under several titles, including "Innocence of Muslims". The film depicted the Prophet Mohammad in terms seen as blasphemous by Muslims and was condemned by Washington.
The film briefly united Houthi Shi'ite Muslim rebels based in northern Yemen with their traditional rivals, Sunni Muslim Salafists, at the protest.
Witnesses said security forces in Yemen made no effort to stop the demonstrators when they first began marching towards the embassy compound holding banners declaring 'God is Greatest'. Some scaled the embassy gate as tires blazed outside.
The protesters threw stones and some smashed light bulbs and signs before attacking the security offices and the compound. Yemen state television showed protesters using a forklift truck to remove a vehicle, while one of them battered it with a stick.
President Abd-Rabbu Mansour Hadi offered "a personal apology" to President Barack Obama over the incident and ordered a swift investigation.
Hadi blamed "mob-like groups" bent on harming Yemeni-U.S. relations for the attack and promised to ensure they are properly punished, state news agency Saba said.
A Yemeni security source said Interior Minister Abdul Qader Qahtan personally oversaw the deployment of riot control forces to the area, to clear the protesters from inside the compound.
Dozens of youths later regrouped and tried to break into the compound from the back, but the Yemeni government pushed extra armored forces to the area, ringing the whole district where the U.S. embassy, the British embassy and a hotel often used by foreign diplomats is located.
Yemen, a key U.S. ally, is struggling against multiple challenges since mass protests forced long-serving President Ali Abdullah Saleh to step down last year.
The United States, eager to help Yemen recover from the upheaval that put the state on the verge of collapse, has said it would provide $345 million in security, humanitarian and development assistance this year, over double last year's aid.
Yemen is home of Al Qaeda in the Arabian Peninsula (AQAP), which is viewed by Washington as the most dangerous branch of the militant network established by Osama bin Laden.
(Additional reporting by Sami Aboudi in Dubai and Raissa Kasolowsky in Abu Dhabi, editing by Philippa Fletcher)