Update: Samuel Sheinbein, an American who fled to Israel after murdering Enrique Tello Jr. in 1997, was killed in a shootout with a Yamam SWAT team on Sunday evening.
As he was being moved to a different cell, Sheinbein apparently stole (or somehow acquired) a gun and shot 3 guards. He then blockaded himself in his cell, shooting an additional 2 to possibly 5 more guards.
SWAT teams stormed the Rimonim prison and killed Sheinbein.
A few weeks ago, the prison system had to release Sheinbein for a furlough, as per orders from the Israeli Supreme Court and against the wishes of the prison system. During his day off, Sheinbein stole a gun in Ramle, but was quickly apprehended.