The Gaza Strip has been under degrees of lockdown since 2007, when Israel and Egypt imposed blockades after the militant group Hamas took control of the impoverished Palestinian territory. The same conditions that make life a daily struggle there, and that have obstructed even the most basic preparations for the looming threat of a coronavirus outbreak, have perhaps made it harder for the virus to find a toehold. That could be about to change.

The few points of entry to the coastal enclave of nearly 2 million people largely closed in March. But on Tuesday, authorities imposed a 48-hour lockdown after reporting the first four confirmed cases of the virus in the general population. By Wednesday, nine more cases had been discovered in two different areas. The territory also reported the first death related to covid-19 contracted through community spread.

For months, aid agencies have warned that the silent transmission of the virus through the conflict-weary strip could be calamitous. Gaza has one of the densest populations on Earth, a collapsed health-care system, and small supplies of electricity and clean water. Health-care workers are bracing for further signs of a wider outbreak among already vulnerable communities.

“Having this happen on top of the existing health system challenges is a matter of concern for us,” said Ayadil Saparbekov, the head of the World Health Organization’s local health emergencies team, according to Reuters. “We have been beefing up our support before this event by providing medical equipment and personal protective equipment as well as laboratory testing equipment.”

Before Tuesday, Gaza had confirmed 109 coronavirus infections and one death, all among people in quarantine. Since March, Hamas has ordered anyone returning to the strip to spend 21 days in a government-run isolation center. International journalists and many humanitarian workers are barred from entering via the designated crossing point with Israel.

The four cases from Tuesday were reported after a woman who procured an Israeli permit to travel from Gaza to Jerusalem for medical reasons tested positive for the virus upon arrival. That led Gaza authorities to uncover a cluster at al-Maghazi refugee camp, where she lived, in a dense and dilapidated neighborhood near the center of the territory. Although all four people who tested positive were members of the same family, authorities quickly imposed a curfew and announced a 48-hour shutdown of businesses, schools, cafes and mosques.

Six of the nine cases reported Wednesday were also in al-Maghazi, which is now under an even stricter lockdown. But three others were reported in the north, signaling wider community spread. The man who died was 61 and passed away while on life support en route to an isolation center, according to the Health Ministry.

As the news spread on Tuesday, residents with the means to do so scrambled to stock up on food and other household necessities, Reuters reported. The unemployment rate in the territory, even according to official numbers, is close to 50 percent, and nearly half the population relies on the United Nations for food aid.

The lockdown comes amid escalating tension in recent days across the Gaza border between Israel and groups linked to Hamas. Palestinian militants have sent incendiary balloons into Israel as part of an effort to pressure Israel to ease the blockade. In response, the Israelis carried out airstrikes on Hamas-linked targets and closed Gaza’s only fishing zone and commercial crossing. Israel also suspended its fuel shipments to the territory’s only power plant, which shut down last week as a result. Daily electricity allocations have been reduced to two to four hours a day.

“We are calling on all concerned parties to maintain a supply of electricity that is sufficient to meet the basic needs of the civilian population,” Matthias Schmale, the director of U.N. Relief and Works Agency affairs in Gaza, said in a statement. “All parties must show utmost restraint and protect the civilian population with full respect for their dignity and human rights.”

Israel and Hamas fought three wars in a decade, plus countless flare-ups. As part of its stifling blockade, Israel prohibits the entry of materials that it says could have a dual purpose in weapons manufacturing. Gaza has faced severe medical shortages and has only about 100 ventilators, half of which are already in use, according to the Associated Press.

Israel, Egypt and Hamas have all imposed further restrictions on entering or exiting the territory in response to the pandemic. It is difficult for Palestinians in Gaza to procure a permit to travel into Israel or the Israeli-occupied West Bank, but many try for better medical care. Rights groups in Israel have called on the government to help facilitate medical access for sick Palestinians now affected by the additional closures.

“If even well equipped health-care systems in European countries have found handling this crisis difficult, then the Palestinian health-care service, which bears the burden of budget shortages and decades-long fragmentation, is likely to fare much worse,” Dana Moss and Ghada Majadle of Physicians for Human Rights Israel wrote in the Lancet.

Hamas, designated a terrorist group by the United States, seized control of the territory in 2007 after it ousted its main Palestinian rival based in the West Bank. Its ultraconservative rule and corruption have angered many Palestinians in Gaza, but under the territory’s repressed conditions, no political alternatives have taken hold.

This report has been updated.