The Palestinians said Friday the situation in Gaza is “extremely fragile” and that Israel’s ceasefire violations and other illegal actions risk undermining the calm that was just restored.

In a letter to the UN Security Council, the Palestinian UN observer Riyad Mansour said Israeli forces on Friday fatally shot Anwar Abdulhadi Qudaih, 21, in the head and injured at least 19 other Palestinian civilians in a border area.

Mansour also accused Israel of intensifying its use of “excessive and lethal force” against Palestinian civilians in the West Bank and East Jerusalem in recent days and of arresting at least 230 Palestinians since the Gaza conflict began.

Some 300 Palestinians approached the Israel-Gaza border fence at several locations in southern Gaza Friday, and tried to damage it and cross into Israel, according to the IDF. Protesters also hurled rocks at Israeli troops. A Palestinian man was reported killed in the clashes.

Soldiers fired warning shots in the air to distance the Palestinians from the fence, but after they attempted to cross into Israel, troops fired at their legs, the military said. It also said a Palestinian infiltrated into Israel in the course of the unrest, but he was returned to Gaza.

In the past, Israel’s military has barred Palestinians from getting close to the fence, and soldiers have opened fire to enforce a no-go zone meant to prevent infiltrations into Israel.

Since the ceasefire, growing numbers of Gazans have entered the no-go zone.

In one incident captured by Associated Press video, several dozen Palestinians, most of them young men, approached the fence, coming close to a group of Israeli soldiers standing on the other side.

During eight days of cross-border fighting between Israel and Hamas, Mansour said more than 160 Palestinians were killed and over 1,230 injured. Israel said 120 of the Gaza fatalities were engaged in terrorist activities. Some 1,500 rockets were fire into Israel from Gaza, killing six Israelis and injuring dozens, despite Israeli anti-missile defenses.