GAZA, May 3 (Xinhua) -- The armed wings of the Palestinian factions, including the Islamic Hamas movement, threatened to retaliate on Israel after three Palestinians were killed in the Gaza Strip earlier on Friday.

The Joint Chamber of Military Operations said in a short press statement that "due to the Zionist aggression on our people, the armed wings of the Palestinian factions are urged to promote the status of readiness to respond to the enemy's crimes."

Earlier on Friday, three Palestinians were killed and 50 wounded in a new wave of tension between Israel and the Palestinians in the Gaza Strip, despite efforts of the mediators to restore calm in the coastal enclave.

Ashraf al-Qedra, Gaza Health Ministry spokesman, earlier told reporters that 19-year-old young man Khalil Abu Tir was killed after he had been shot by Israeli soldiers in his abdomen east of the southern Gaza Strip town of Khan Younis.

Abu Tir was killed during the weekly anti-Israel protests, better known as the Great March of Return and Breaking the Israeli Siege, which started end of March last year.

More than 50 Palestinian demonstrators were injured by Israeli soldiers' gunfire, including 12 children, two females, three paramedics and one female journalist during the clashes in eastern Gaza Strip close to the border with Israel, said the spokesman.

Two Palestinians, one was 33-year-old and one was 29-year- old, were killed in an Israeli airstrike on a military training facility near al-Mughazi refugee camp in central Gaza Strip not far from the border with Israel.

Hamas movement's armed wing al-Qassam Brigades said the two killed men are members in the group and they were killed by the shrapnel of an Israeli missile that was fired from an Israeli army warplane.

According to an Israeli army spokesman, the Israeli airstrike on Hamas military training facility was an immediate response to the shooting attack that wounded two Israeli soldiers, one of them was moderately injured by Gaza militants in eastern Gaza Strip.

The growing escalation between Israel and the Palestinians in the Gaza Strip took place while two delegations, representing Hamas movement and the Islamic Jihad, are holding talks in Cairo with Egyptian security intelligence officials on reaching calm in the coastal enclave.