According to the local newspapers, the zoo worker was treating the crocodile which is sick and had not ate anything for days. The worker used a tranquilizer on the croc but apparently it didn't work. He tried to grab the syringe back (?) and the croc suddenly bite off his arm. Other zoo workers attempted to get his arm back but the croc didn't want to cooperate. They soon called a policeman who shot the croc twice with a hand pistol and the croc finally drop the arm, although it doesn't seem to be harmed. Apparently it didn't take very long time, so the doctor said that the chance of reattaching his arm is very good but may require months of rehabilitation.
This also created a controversy because many local newspapers show big and quite graphic pictures on the front page, and some people think it's not appropriate.