Thousands of Palestinians marched Thursday in funerals for a prisoner who died in Israeli custody and two teenagers fatally shot by Israeli soldiers.

The marches illustrated mounting tensions in the West Bank ahead of a visit this weekend by U.S. Secretary of State John F. Kerry to explore ways to revive peace talks.

Scores of stone-throwing youths clashed with soldiers in the prisoner’s home town of Hebron and at other West Bank flash points, reflecting Palestinian outrage over the deaths and a deepening rift with Israel, complicating Washington’s efforts to prod both sides back to negotiations.

Kerry will meet with Israeli Prime Minister Benjamin Netanyahu and Palestinian Authority President Mahmoud Abbas in an effort to restore shattered trust between them, but the latest violence threatened to cast a pall over the meetings.

“It seems that Israel is seeking to stir up chaos in the Palestinian territories,” Abbas said at a meeting of top officials of his Fatah party. “From the beginning, we have said that we want security, calm and stability, and despite that, Israel on every occasion is using lethal force against peaceful young protesters. Peaceful demonstrations are suppressed by force of arms, and that is totally unacceptable.”

The Israeli army said it was investigating an incident Wednesday night in which soldiers fatally shot two Palestinian teenagers in a confrontation near the city of Tulkarm.

A military spokeswoman said troops in a fortified watchtower near an Israeli settlement opened fire when a group of Palestinians, who were spotted approaching the position, hurled molotov cocktails at the post.

Palestinian medical officials said Amer Nassar, 17, and Naji Balbisi, 18, were shot in the chest. Balbisi’s body was found hours after the incident. The Israeli army said another youth was arrested.

The Palestinian Center for Human Rights, which investigated the clash, said that the protesters had pelted watchtowers at a checkpoint with stones and empty bottles, drawing live fire, and that in addition to the two youths who were killed, a third was wounded.

Hundreds turned out for the teenagers’ funeral in their home town, Anabta, where their bodies were carried through chanting crowds by uniformed security officers.

Thousands also gathered in Hebron for the funeral of the prisoner, Maysara Abu Hamdiya, 63, whose death from cancer in an Israeli hospital Tuesday set off street protests and accusations by Palestinian officials of medical negligence by prison authorities.

The charges were repeated Thursday by the Palestinian minister of prisoner affairs, Issa Qaraqa, who said Israel had committed a “crime” by failing to provide Abu Hamdiya with proper medical care. An affidavit taken by a lawyer who visited the prisoner last month said that though he had complained of severe throat pain in August, his condition was not examined in a hospital until January, when cancerous cells were found.

Results of an autopsy conducted Wednesday by Israeli authorities showed that Abu Hamdiya, a smoker, had metastatic cancer that had spread from his throat to his lungs, liver and spine. A spokeswoman for the Israel Prison Service said that Abu Hamdiya had been taken to the hospital several times after his cancer was diagnosed and that a committee would review the handling of his case.

Abu Hamdiya, a retired general in the Palestinian security services, was buried with military honors, his body wrapped in a Palestinian flag. He was arrested by the Israelis at the height of the Palestinian uprising in 2002 and given a life sentence for helping organize a suicide bombing attempt at a Jerusalem cafe.

Shops were shuttered Thursday in Hebron, and crowds of youths fought street battles with soldiers, hurling stones and molotov cocktails that were met with volleys of tear gas and rubber-coated bullets, the Israeli army said. Clashes also were reported at the al-Arrub refugee camp and in Beit Umar, on the main road from Jerusalem to Hebron.

In southern Israel, a rocket fired from the Gaza Strip landed in an open area early Thursday, causing no casualties or damage, a police spokesman said. It was the fourth rocket reported to have hit Israel since the prisoner’s death.

An al-Qaeda-inspired group asserted responsibility for the earlier rocket attacks, which triggered an Israeli airstrike in Gaza late Tuesday, the first since a cease-fire ended eight days of cross-border fighting in November.

There was no immediate military response Thursday, but Netanyahu warned: “If the quiet is violated, we will respond with force.”