Hamas gunmen stormed the home of a militant from the rival Fatah movement on Friday, witnesses said, sparking a deadly gunbattle and capping a day of factional violence that killed at least 13 people, including a two-year-old boy, across the Gaza Strip.
Friday's violence was among the deadliest in nearly two months of infighting and marred the first anniversary of Hamas' upset victory in Palestinian elections.
After nightfall, the fighting showed no signs of slowing, as the sound of gunfire echoed throughout Gaza City.
Some of the heaviest shooting was concentrated around the home of Mansour Shaleil, a local Fatah leader in the Jebaliya refugee camp just north of Gaza City.
Hamas gunmen surrounded the home on Friday to arrest Shaleil, accusing him of involvement in a shooting that killed two Hamas supporters earlier in the day.
After an hours-long standoff, dozens of Hamas gunmen stormed the house and exchanged fire with Shaleil and his loyalists, according to witnesses and ambulance drivers.
They later withdrew, Palestinian media reported, leaving Shaleil unharmed. Two people were killed in the fighting. The men were identified as Hamas militants.
"It looks like they forgot who the enemy is," said Maher Mekdad, a Fatah spokesman. "They forgot the Israeli occupation."
Fatah gunmen, meanwhile, abducted 19 Hamas militants and threatened to kill them if Shaleil was harmed, officials on both sides said.
After Shaleil's rescue, Hamas and Fatah officials said they were working with mediators to arrange the hostages' release.