BENGHAZI – Libya said Thursday it has made arrests and opened a probe into an attack on the US consulate in Benghazi that killed the American ambassador, amid speculation that Al-Qaeda rather than a frenzied mob was to blame. “The interior and justice ministries have begun their investigations and evidence gathering and some people have been arrested,” Deputy Interior Minister Wanis Al-Sharif said in the Libyan capital. He declined to give any details of the number of people in custody or their backgrounds “so as not to hamper the smooth running of the investigation.” “All measures are being taken. An independent judicial committee has been set up to carry out an inquiry,” Abdelmonem Al-Horr, spokesman for the interior ministry's security commission, said. FBI probing Benghazi deaths In Washington, Attorney General Eric Holder said the FBI has opened an investigation into the deaths of the four people killed in the attack on the US consulate in Benghazi. The attorney general made the comments in remarks prepared for delivery Thursday in Doha, Qatar. The attorney general is in the region this week for meetings with his foreign counterparts. In Doha, the attorney general said the US is committed to working with the Libyan government to seek justice for the deaths of Ambassador Chris Stevens and three other Americans at the consulate. US officials said a detachment of 50 Marines had been dispatched to secure the American embassy in Tripoli, where staff numbers were being cut to emergency levels. Washington also decided to evacuate all its staff from its mission in Benghazi while at the same time sending two destroyers to “the vicinity of Libya”, a senior US official said. – Agencies