The citizens of the Gaza Strip are caught in the crossfire in the ongoing tensions between the militant group Hamas that controls Palestinian lands and Israeli forces after Hamas launched an incursion on Israel.

The Israel Defense Forces says it struck 130 targets in Gaza within just three hours Monday morning. The country's military forces say they are in "a state of alert for war" after Hamas' "unprecedented" attack Saturday in which they fired hundreds of rockets and sent roughly a thousand troops into Israel territories.

Palestinian authorities said at least 560 people have been killed and another 2,900 have been injured in Gaza due to Israeli retaliatory attacks.

In Israel, at least 900 people have died and more than 2,300 others have been injured by Hamas forces.

According to the United Nations, roughly 6,400 Palestinians and 300 Israelis had been killed in the ongoing conflict since 2008, not counting the recent fatalities.

At least 33 Palestinian children were killed in the retaliatory airstrikes launched into Gaza by Israel, according to the advocacy group Defense for Children Palestine.

Hundreds of apartments and homes have been destroyed in the Gaza Strip, including refugee camps, leaving more than 123,000 people displaced, according to the United Nations.

More than 73,000 people are sheltering in schools, while hospitals struggle to cope with the numbers of injured.

Gaza's main hospital, Beit Hanoun Hospital, has been damaged and is now out of service after Israeli forces repeatedly targeted the area, according to the Gaza Health Ministry.

A main communication center in Gaza was also destroyed from airstrikes, making it difficult to get internet access or make phone calls.

Unlike Israel, the Gaza Strip has no air raid sirens or bomb shelters.

"Hospitals are overcrowded with injured people, there is a shortage of drugs and [medical supplies], and a shortage of fuel for generators," said Ayman Al-Djaroucha, deputy coordinator of Doctors Without Border/Médecins Sans Frontières (MSF) in Gaza, in a statement.

"Ambulances can't be used right now because they're being hit by airstrikes," said Darwin Diaz, MSF medical coordinator in Gaza, in a statement.

Defense Minister Yoav Gallant said that all food, fuel, electricity, and other necessities will be blocked from entering the Gaza Strip.

This is the most recent battle in the longstanding Israel-Palestine conflict spurred by centuries-old disputes over land ownership, including the Israeli occupation of the Palestinian territories of East Jerusalem, the West Bank, and Gaza in the 1960s and the takeover of Palestine by Hamas in the 2000s which led to a blockade imposed by neighboring Israel and Egypt in 2007.

Human rights organizations fear this will only exacerbate the humanitarian crisis in Palestinian territories that has been worsened by the blockade.

According to the United Nations, 81% of the population in Gaza lives in poverty with food insecurity plaguing 63% of Gaza citizens. The poverty rate is 46.6%, and access to clean water and electricity remains inaccessible at "crisis" levels, the agency states.

Terre des hommes (TDH), the leading Swiss children's rights organization, has been active in the region for 50 years and is concerned about intensifying violence.

"We call all parties to the conflict to respect the International humanitarian Law and the Geneva Conventions. Civilians and civilian objects must be respected and protected at all times. Buildings used by civilians, such as schools, hospitals and emergency shelters, must not become targets under any circumstances," said Barbara Hintermann, Director General of TDH, in a statement.