Two Palestinian teenagers was killed when an artillery shell left behind by Israeli forces exploded in Gaza Friday morning, medics said.

Gaza medical services spokesman Adham Abu Salmiya said 16-year-old Victor Batniji was dead when he arrived at Gaza City's Shifa Hospital. Moumin Helles, also 16, died shortly after arriving at the hospital, after being wounded in the same incident in the Shujaiyya area.

An Israeli military spokesman said the army was aware of an explosion in the area but "nothing IDF [Israel Defense Forces] related."

Three people were also injured by Israeli fire in the "buffer zone" along the border with Israel.

Abu Salmiya said two men in their 20s arrived at Kamal Udwan hospital in Beit Lahiya after being shot in the legs by Israeli forces after venturing into the northern "buffer zone" near the Israeli border to collect firewood.

In another shooting, local sources said a 16-year-old boy was also shot in the leg by Israeli soldiers while working on his family's farm in the village of Khuza'a, near Khan Younis. He was taken to Nasser Hospital in Khan Younis, according to Abu Salmiya.

The Israeli spokesman confirmed that soldiers shot three people, two in Beit Lahiya, in the north, and one near Khan Younis in the south. In both cases, he said, soldiers spotted Palestinians approaching the border, then fired warning shots before shooting at their lower bodies.

Earlier Israeli warships fired on Israeli fishing boats off the coast of Deir Al-Balah and Khan Younis, according to sources in Gaza. No one was reported injured.

Separately, the armed wing of Islamic Jihad, Al-Quds Brigades, said it fired several mortars at Israeli special forces near the Kissufim military installation.