Yemeni authorities have arrested 30 people suspected of belonging to Al-Qaeda following an attack on the heavily fortified US embassy in Sana'a, a security source said on Thursday. Two suicide car bombs set off a series of explosions outside the embassy compound on Wednesday, killing 16 people including six attackers. The dead were all Yemeni apart from an Indian woman who was walking past. “The security authorities want to investigate whether the suspects are linked to Wednesday's attack,” the security source said, adding that Washington would send investigators to Yemen to help the authorities. The heavily guarded embassy is located in the affluent Dhahr Himyar district, a residential area dotted with five-star hotels and other embassies. The attackers, some dressed in army uniforms, were stopped short of the compound's walls by guards and massive security barriers, but civilians waiting in line for visas outside the embassy were among the casualties. Three police officers and seven civilians were injured, including children in a residential compound across the street from the embassy, home to many Westerners. Snipers hidden across the street fired on emergency personnel rushing to the scene. Yemeni security sources said special counterterrorism forces had been put in charge of defending the US embassy. Yemeni security forces set up check points in Sanaa, particularly around embassies and areas where foreign diplomats and business people live. President George W. Bush called the attack “a reminder that we are at war with extremists who will murder innocent people to achieve their ideological objectives.” The US counts Yemen as an ally in the war on terrorism. Yemen has been a focus of American counterterrorism efforts ever since the 2000 Cole attack, in which 17 American sailors were killed by suicide bombers on a boat.A similar attack two years later hit a French oil tanker, killing one person.