I went to the Hebrew website of the Israeli newspaper Yediot Aharonot, and found an article that revealed the reason for the helicopter. What follows is my translation.
Fire in Silwan: They are abusing the residents of the house of Abu Nab
Left-wing activists and residents in the east Jerusalem neighborhood told Ynet that the violent disturbances began when guards broke into the house of Abu Nab, which right-wing activists have threatened to clear out soon. “They fired in every direction,” they said.See also the report in Haaretz: East Jerusalem fracas.
The violent confrontations that broke out tonight in Silwan in east Jerusalem perhaps hint at the disturbances which are likely to flame up if right-wing activists execute their threats to clear out the house of Abu Nab themselves; in the past the house was a synagogue. In the confrontations six policemen and four security guards were lightly injured. According to the Association for Civil Rights in Israel (ACRI), tens of Palestinians were injured by inhaling smoke.
According to left-wing activists and Arab residents in Silwan, tonight’s events began after private security guards came into the new “House of Contention,” the house of Abu Nab. According to the residents, the security guards attempted to break into the house, and when they found it locked, they began to fire tear gas inside it. In the end, they succeeded in breaking past the doors, and a few minutes, many residents of the village began to confront them.
Avner, one of the leftwing activists who is in contact with the Arab residents, said to Ynet that this was a provocation by the police, who are trying to inflame the area to prevent the evacuation of Beit Yehonatan. “The residents there were dragged into a violent confrontation, the police and Border Police have been wandering around in the last few days and trying to incite the area after the quiet demonstration we held in the place on last Friday,” he said.
Nasrin Elian from ACRI said that “The security guards from the settlers confronted the residents, in the context of the threat of MK Uri Ariel, that if the house of Abu Nab isn’t cleared by July 4, they will clear it out by themselves. What happened is that once again there were provocations by the security guards near Beit Yehonatan and Beit Ha-Dvash. Many young people gathered together, and the guards began to fire in all directions. Everyone who came near to the house, they shot in his direction.”
Elian also said that the security forces fired tear gas into the house of Abu Nab. “All of the residents, about 40 people, were suffocating and went outside, among them a girl of five who fainted and lost consciousness, and a pregnant woman who also fainted. There was a helicopter in the air with a light beam that lit in every direction, and the ambulances were coming back and forth loading injured people. The residents report about tens of injured, among them two severely.” The police report that they do not know about the injured.
The chairman of the Meretz faction in the Jerusalem city council, Joseph (Pepe) Alalu, who resigned from the coalition after the mayor, Nir Barkat, advanced the King’s Garden plans, blamed him for the disturbances: “When the hammer throws a stone in the water, after that even a hundred wise men can’t take it out from there. We knew, we warned, and the thing that is the worst is that even Nir Barkat knows the sensitivity of the situation. The residents of Silwan, at the moment that the discussions began about the plan, saw themselves deceived again and again. They proposed their own plan, but the municipality did not deal with it at all. It’s a shame that because of a plan like this disturbances have begun now.”
Hagit Ofran of Peace Now just reported on these events in Silwan in an article in the Huffington Post - her report covers a wide range of what's been happening in east Jerusalem, the provocations of the settlers and the Wild West actions of the Border Police.