He added: "We know he is still armed and considered dangerous.”
One report suggested he was a disgruntled former employee who may have sought revenge after being dismissed from duty.
Security camera footage shared online appeared to show the Palestinian fleeing the site with a gun.

Police sources said the weapon he used was a homemade Carl Gustav rifle, known locally as a “Carlo”, and that it appeared to be a “lone-wolf attack”.
Prime Minister Benjamin Netanyahu expressed his condolences and said he was “sure we will bring the terrorist to justice soon”, Haaretz reported.
President Reuven Rivlin said: “This was not only an attack on innocent people going about their daily lives, it was also an attack on the possibility of Israelis and Palestinians co-existing peacefully.
“I call on the Palestinian leadership to condemn this murderous attack and to use the forces at their disposal to capture the terrorist and those who aided him.”