Demonstrators stormed the US embassy in Yemen on Thursday, leading to a clash in which one person was killed, while protesters stoned Washington's mission in Cairo as anger spread over a US-produced film mocking Islam.Yemeni police used water cannon and fired warning shots to expel protesters who breached the perimeter wall, and at least one demonstrator was shot dead outside the compound as police battled to prevent any new incursion.The protests came even as US and Libyan officials said they were probing a mob attack on the consulate in Benghazi that killed the ambassador and three other US officials on Tuesday, amid growing speculation it was the work of jihadist militants rather than just demonstrators.In the Yemeni capital Sanaa, five protesters were also wounded when police opened fire outside the compound, a security official said.The shooting came as protesters, chanting "O, messenger of Allah... O, Mohammed," launched a second charge on the complex which they had stormed earlier but were ejected by the security forces.President Abdrabuh Mansur Hadi apologised to his US counterpart Barack Obama and the American people for the acts of a "mob" and ordered a probe."Those who are behind (the attack) are a mob that are not aware of the far-reaching plots of Zionist forces, especially those who made a film insulting the Prophet," said Hadi.Some protesters said they saw three vehicles being torched by some of the demonstrators after they gained access to the compound through an unguarded security gate.After being evicted from the complex on their first assault, protesters retreated about 100 metres (yards) from the gate, gathering near a checkpoint where they chanted anti-Jewish slogans.They then launched a second bid to access the compound, prompting police to fire on the crowd, witnesses said.In the Egyptian capital Cairo, police fired tear gas to disperse the latest protest outside the embassy by stone- and bottle-throwing demonstrators.A total of 70 people were injured, the health ministry said.Armoured vehicles were deployed around the mission, an AFP correspondent reported.On Tuesday night, protesters stormed the Cairo embassy compound, tearing down the Stars and Stripes and replacing it with a black Islamic flag.Egypt's Islamist President Mohammed Morsi condemned the offence caused by the movie but warned against resorting to violence."We Egyptians reject any kind of assault or insult against our prophet. I condemn and oppose all who... insult our Prophet," he said in remarks broadcast by state television."(But) it is our duty to protect our guests and visitors from abroad," Morsi said. "I call on everyone to take that into consideration, not to violate Egyptian law... not to assault embassies."-- 'Disgusting and reprehensible' --------------------------------------The low-budget movie in which actors have strong American accents, portrays Muslims as immoral and gratuitously violent.US Secretary of State Hillary Clinton on Thursday condemned the film, stressing that the US government had nothing to do with it."To us, to me personally, this video is disgusting and reprehensible. It appears to have a deeply cynical purpose, to denigrate a great religion and to provoke rage," Clinton said."The United States government had absolutely nothing to do with this video. We absolutely reject its content and message."But she reiterated: "There is no justification, none at all, for responding to this video with violence."Saudi Arabia, home to Islam's holiest sites, on Thursday condemned both the release of an amateur movie mocking Islam and the deadly attacks against US missions.Libya's new Prime Minister Mustafa Abu Shagur told AFP in an exclusive interview that there had been a "big advance" in the investigation into the attack on the US consulate in Benghazi.Deputy Interior Minister Wanis al-Sharif said that arrests had been made but declined to elaborate on the number of people in custody or their backgrounds "so as not to hamper the smooth running of the investigation.""The interior and justice ministries have begun their investigations and evidence gathering and some people have been arrested," Sharif told AFP.Journalists managed to enter the Benghazi residential complex that housed the US consulate and described a scene from a warzone.Blood stained the ground at the main entrance of the consulate, which is part of a three-building compound, an AFP photographer said.All the buildings were blackened by fire, furniture destroyed and walls punctured by bullets, said the photographer who managed to enter the grounds with other journalists after obtaining permission from the owner of the compound.Security officers and police were nowhere to be seen, inside or outside the consulate, with no sign of an investigation.Tuesday's assault was initially believed to have been motivated by outrage over an amateur Internet film made in America that insulted Islam, but US officials later said it might have been a pre-meditated assault by Al-Qaeda affiliates or sympathisers.A spokesman for the Libyan interior ministry's security commission said the inquiry would be "very complicated" because the crowd outside the consulate had been very mixed."There were extremists, ordinary citizens, women, children and criminals," Abdelmonem al-Horr told AFP.Protests against were also held in Iraq and Iran as anger over the US-produced movie "Innocence of Muslims" that initially erupted among Sunni Muslims spread to the two Shiite-majority countries.A small demonstration was also held by Israeli Arabs outside the US embassy in Tel Aviv.