CAIRO - A leading human rights activist has called for an immediate investigation of reports that guards deliberately killed dozens of inmates at an Egyptian prison during the chaotic first days of Egypt's uprising. At least 65 prisoners are believed to have been killed at al-Qatta prison on the outskirts of Cairo, human rights campaigner Hossam Bahgat, citing testimony by inmates and their relatives, told The Associated Press. Thousands of prisoners across Egypt are believed to have escaped or been set free shortly after the revolt against long-time President Hosni Mubarak erupted Jan. 25. Bahgat said he and other activists are still trying to piece together what happened at the prisons. The unrest at al-Qatta broke out three days after the start of the uprising, when some prisoners attempted to escape and guards responded with force, Bahgat told reporters. He said guards climbed onto watchtowers and started shooting live rounds "in an attempt to kill as many people as possible, and not in an attempt to deter the chaos, as regulated by the prison law". Following the initial violence, during which a senior officer was killed, "there were three days in which inmates were executed in retaliation, it seems," according to Bahgat, the head of an Egyptian human rights group. Water and electricity at the prison were cut off for a week, he said. Bahgat said he filed a complaint with the prosecutor general seeking an immediate investigation into the allegations. The prosecutor's office could not immediately be reached for comment.