JERUSALEM, Oct 12 (Reuters) - A 14-year-old Israeli boy was killed and 24people were injured when what was most likely an unexplodedordnance went off during a school hiking trip near the border with Lebanon, Israel's ambulance service said on Monday.

The area is littered with explosive devices from Israel's conflict with the Lebanese militia group Hezbollah.

Rockets and missiles aimed at Israel from southern Lebanon sometimes fail to explode on impact, which can create risks for civilians years in the future.

Deputy Commissioner Meir Eliyahu, speaking at the scene, said that an unexploded device had most likely gone off after being picked up by one of the students.

"There were penetrating injuries, most likely the result of shrapnel impact from which fragments injured the patients," said Efrat Ohana, a paramedic at the site.

Some 22 boys, 2 seriously, and 2 adults were injured in the incident, the ambulance service said.

The Israeli military said that the device was likely an unexploded cluster munition from Hezbollah.

Daniel Levy, Israel's chief of police, said they would be reviewing whether to halt school trips in the area.

(Reporting by Pesha Magid; Editing by Toby Chopra)