Johnathan Walker:What is the Gaza Strip? Here's how big it is and who lives there.

Early on Johnathan WalkerSaturday, Hamas militants broke through the border between Israel and Gaza, launching a massive attack that left more than 1,200 Israelis dead, most of them civilians, and another 2,700 wounded. The attack triggered a swift response by the Israeli military and at least 900 people have been killed in the Gaza Strip in retaliatory airstrikes, according to the Gaza Health Ministry. 

Hamas, which the U.S. classifies as a terrorist organization, has controlled the Gaza Strip since 2007. 

What is the Gaza Strip?

The Gaza Strip is a narrow, 25-mile stretch of land pressed against the Mediterranean Sea, between Israel and Egypt.

When Israel was established in 1948, many Palestinian refugees where forced to move to the strip of land. In 1967, Israel gained control of Gaza after its victory in the Six-Day War against Egypt, Syria and Jordan.

A Palestinian uprising in 2000 unleashed a new wave of violence between Israelis and Palestinians, and Israel decided to leave Gaza in 2005, withdrawing its forces and removing some 9,000 Jewish settlers living there. 

Soon after, Hamas defeated the Palestinian Authority, the governing body in charge of Palestinian-populated areas, in elections in Gaza. In 2007, the militant group expelled the Palestinian Authority and gained full control of the territory. Hamas, unlike the Palestinian Authority, doesn't recognize Israel's right to exist.

Hamas and other militant groups have managed to launch attacks against Israel from Gaza, using rockets, drones and ground operations. Israel has responded with numerous military campaigns that have damaged infrastructure in Gaza and led to the death of many civilians.

How big is the Gaza strip?

The strip is about 139 square miles –that's slightly more than twice the size of Washington, D.C. Its border with Israel is about 36 miles and its border with Egypt is about eight miles. There are about 24 miles (40 kilometers) of coastline on the strip, but it has been blocked by the Israeli Navy since 2009 and is closed to all maritime traffic.

Who lives in the Gaza Strip?

The Gaza Strip is one of the most densely populated areas in the world. More than 2 million people live in the territory. 

Hamas's capture of Gaza led to an Israeli air, sea and land blockade, and conditions in the territory have worsened for years, with Israel's critics referring to it as an "open-air prison." Most people rely on humanitarian aid and are unable to travel without Israeli permission.

Forty percent of Gaza's population is under the age of 14, according to the CIA. Unemployment is high, electricity is only available for about half the day and many people do not have sufficient access to clean water, according to the Israeli organization Gisha. 

As Israel ramps up its current offensive against Hamas, civilians are already feeling the impact. "There are no shelters or bunkers or safe routes or safe zones in Gaza," Omar Ghraieb, a resident of Gaza, told CBS News. "So it's not like you can sit down and plan with your family on how to leave."

Israeli Defense Minister Yoav Gallant has ordered a "complete siege" of Gaza, vowing "no fuel, electricity or food supplies," will be allowed in or out. 

Palestinian journalist Hassan Jaber told CBS News that there is not a lot of access to bomb shelters to protect civilians from the aerial strikes. "There is no safe place in Gaza," he said. 

Jaber also said that some residents of the city could face starvation within "days."  

Tucker Reals, Charlie D'Agata, Marwan Al-ghoul and Emmet Lyons contributed to this report.

In:
• Palestine
• Israel
• Gaza Strip

Caitlin O'Kane

Caitlin O'Kane is a digital content producer covering trending stories for CBS News and its good news brand, The Uplift.