Twenty-seven Palestinians were killed by the Israeli military in the West Bank in 2013, more than triple the number killed in the previous year, according to an annual report published late Monday by Israeli human rights NGO B’Tselem.

The study found that for the first time in 10 years, more Palestinians were killed in the West Bank than in the Gaza Strip.

The group reported 21 fatal incidents in the West Bank during 2013, versus seven altercations in Gaza that left nine Palestinians dead.

In 2012, Israeli security forces killed eight Palestinians in the West Bank and 246 in Gaza, 167 of them during Operation Pillar of Defense. According to B’Tselem, 104 of the 246 were non-combatants.

Nine of the deadly altercations in the West Bank in 2013 occurred during IDF operations to make arrests in the area that turned violent when local Palestinians hurled rocks or shot at Israeli troops, the group said. In one case, the organization was not able to confirm IDF claims that an exchange of fire had taken place.

Another seven incidents occurred during rock-throwing attacks by Palestinians.

The organization also noted that two Palestinians — a resident of the West Bank and a resident of the Gaza Strip — were shot to death inside Israel in 2013.

Three Israelis were killed by Palestinians in the same year, two in the West Bank and one near the fence between Israel and the Gaza Strip.

In its report, the human rights organization criticized Israeli security forces for failing to investigate the deaths thoroughly and closing some cases before reaching a verdict — if a case was opened at all.

“The sharp rise in human casualties in the West Bank only serves to increase concerns that nobody is being held accountable,” B’tselem executive director Jessica Montell said.

“Even though investigations begin almost automatically, the method of investigation has essentially remained the same: it is a slow and cumbersome system in which decisions are reached many years after the fact. A system in which almost nobody is brought to justice for killing Palestinians cannot act as a deterrent, and reflects a lack of respect for human life.”