Around 18,000 residents who have lived through a government siege for more than a year are thought to remain in the camp
Militants from the Islamic State group seized control of most of the Yarmouk Palestinian refugee camp in southern Damascus on Wednesday, according to witnesses in the camp and a Palestinian official.
“Islamic State fighters entered the West side of the camp this morning,"Ahmad, a 30-year-old media activist and resident of Yarmouk camp who did not wish to be identified, told Middle East Eye via Skype.
Ahmad said that gun battles between IS and Palestinian group, Aknaf Beit al Maqdis, opposed to Syrian president Bashar al-Assad, had raged throughout the day in several of the camp's neighbourhoods.
"There were injuries on both sides, light weaponry and RPG missiles are being fired," he said.
Yarmouk was once a thriving neighbourhood home to 160,000 Palestinian refugees and Syrians, but has been caught up in the country's fighting and besieged by government forces for more than a year.
Around 18,000 residents are estimated to remain in the area after many fled the fighting.
Although it is called a camp, Yarmouk - established in the 1950s - is hardly distinguishable, as are many other Palestinian refugee camps in other countries, from many neighbourhoods in Syria today.
The ongoing clashes between Islamic State and Palestinian factions within the camp came days after Aknaf Beit al Maqdis, closely affiliated with Hamas, arrested members of IS operating within the camp, said Ahmad.
"On top of that the Syrian regime has been bombing the camp day in day out with morter shells and artillery," said Ahmad.
"Yesterday a shell hit the ambulance entrance of the Palestinian Hospital, several paramedics were injured."
Syrian rebels withdrew from the camp in February 2014 under a deal that left only Palestinian anti-government groups inside.
The Syrian government's siege - supplies moved in and out of the camp are tightly restricted - has caused significant shortages of food, water and drugs.
IS, which has seized control of large parts of Syria and Iraq, has fought not only against the Assad government but also against other rebel groups as it seeks to expand the territory under its control.
— Ⓐhmad (@ANimer) April 1, 2015
Also Wednesday, rebels backed by the al-Nusra Front seized control of the last border crossing with Jordan that had been under regime control.
"Armed groups, joined today by al-Qaeda affiliate Al-Nusra Front, took over the Nasib border point from regime soldiers" on the Syrian side, said Rami Abdel Rahman of the Syrian Observatory for Human Rights, AFP reported.
Abdel Rahman said the takeover meant there was "no longer a regime presence on the border with Jordan".
A coalition of rebel groups had launched the offensive Tuesday, and al-Nusra joined them late Wednesday.
A pro-regime security source said the "Syrian army withdrew from the Nasib border crossing", according to AFP.
Not long afterwards, regime helicopters began to drop barrel bombs on rebel positions around Nasib, the Observatory director said.
Jordan had said earlier that it closed the crossing to both travellers and goods, AFP reported.
It was a "preventive measure to safeguard the lives and security of travellers due to the fighting underway on the other side of the border", Interior Minister Hussein Majali told AFP.