The residents were attending a party in the building at the time of the fire. Witnesses reported hearing screams but being unable to intervene due to the intensity of the fire.
Officials report that a fire in a residential building in a refugee camp in the Gaza Strip has killed at least 21 people and injured several others.
It took firefighters over an hour to extinguish the fire that broke out on the fourth floor of a four-story residential building in the densely populated refugee camp of Jabalia.
Residents were attending a party in the building, and witnesses reported hearing screams but were unable to assist that inside due to the intensity of the fire.
The UN agency for Palestinian refugees (UNRWA) tweeted that eight children, four women, and a retired UNRWA employee were among those killed.
The injured were transported by ambulance to local hospitals, and Israel, which maintains a blockade on Gaza along with Egypt, said it would allow in those in need of medical treatment.
According to the Interior Ministry of Gaza, an initial investigation revealed that large quantities of gasoline were stored at the site, which fueled the fire. It was unclear how gasoline caught fire.
Large crowds gather in front of the building, while Hamas police officers assess the situation from within.
President Mahmoud Abbas of the Palestinian Authority termed it a national tragedy and declared a day of mourning.
Hussein al-sheik, secretary-general of the executive committee of the Palestine Liberation Organization (PLO), said in a statement that the Palestinian Authority has urged Israel to open the Erez crossing with Gaza so that serious cases can be transported out of the enclave for treatment, if necessary.
Benny Gantz, the Israeli minister of defense, tweeted that his staff would help evacuate the injured.
Jabalia is one of eight refugee camps in Gaza, which is home to 2.3 million people and has one of the highest population densities in the world.
Gaza, which is governed by the Palestinian militant group Hamas and is subject to a crippling Israeli-Egyptian blockade, is experiencing an energy crisis.
In preparation for winter, people frequently store gasoline and cooking gas in their homes, and house fires have historically been caused by candles and gas leaks.
