One diplomat said the attack was not a suicide bombing and that the Yemeni investigation was ongoing. The description of the attack as a bombing differs from what a Yemeni official told CNN last week. The official, who asked not to be identified, said that Saleh was in the mosque when two projectiles were fired during Friday prayers. Supporters of Sadeq Al-Ahmar, leader of the Hashed tribe and an opponent of the Yemeni government, were suspected in the attack. In response, Yemeni security forces shelled Al-Ahmar's home Friday, killing 10 people and wounding 35 others, according to Fawzi Al-Jaradi, an official with the Hashed tribal confederation. After Saleh was taken to Saudi Arabia for treatment, the tribal leader and Vice President Abed Rabbo Mansour Hadi -- Yemen's interim leader -- agreed on a cease-fire, said Abdulqawi Al-Qaisi, spokesman for the Hashed leader. Yemen's largest opposition bloc has vowed to prevent Saleh from returning. The Yemeni people will do all in their power to not allow Saleh to re-enter the country, Joint Meeting Parties spokesman Mohammed Qahtan said Sunday. A U.S. government official said Monday he could not imagine the Saudis letting Saleh return. He said it was critical that the Saudis press Saleh to accept a Gulf Cooperation Council deal offering him immunity in exchange for stepping down. Saudi state-run Ekhbariya television reported Monday