An Israeli judicial inquiry has ruled out prosecuting police officers who shot dead 13 Israeli Arabs during a violent demonstration in 2000.
The report said shooting into the crowd may have been justified
The inquiry into the shootings said there was insufficient evidence to incriminate or identify the officers.
The 13 men died when police fired into pro-Palestinian demonstrations that broke out days after the start of the latest intifada, or uprising.
Relatives of the dead say they will fight the "unjust" ruling.
"I ask for every citizen of Israel to stand up and scream for the law to be changed," said Jamila Assaleh, the mother of a 17-year-old who was killed.
"I feel anger, fury, sadness," she told Reuters news agency.
An Israeli Arab MP, Azmi Bishara, said he had expected the commission to "cover up the crime instead of finding people guilty in the security forces".
Israel's Arab minority accounts for 20% of the population and is descended from Palestinians who chose to remain in the Jewish state when it was created in 1948.
They often complain of being treated as second-class citizens by the Israeli authorities.
The judicial report said: "There is no alternative but to close all of the cases, some because of lack of sufficient evidence, and some because, to our regret, we have not managed to locate the responsible police officers."
The commission said the police decision to fire bullets at the legs of some of the protesters may have been justified.
The start of the second Palestinian intifada in 2000 sparked rioting among Arabs in northern Israel.
Petrol bombs were thrown at security forces and a Jewish motorist was killed by a rock.
A 2003 government report into the police response to the riots recommended that officers should be reprimanded but not charged.