The UN Security Council responded quickly to a request from Lebanon's prime minister and gave approval Thursday for UN investigators to help probe the latest bombing in the country. Prime Minister Fuad Saniora sent a letter to Secretary-General Ban Ki-moon on Tuesday requesting technical assistance from the International Independent Investigation Commission, which was established to investigate the Feb. 14, 2005, assassination of former prime minister Rafik Hariri. Lebanon has been hit by a string of bombings since the one that killed Hariri, most of them targeting prominent anti-Syrian figures. Tuesday's bombing of two buses outside Beirut was the first that appeared intended to cause maximum casualties among civilians. Saniora said three people were killed and 22 injured.