Jerusalem ( CNN ) -- Two 16-year-old Palestinian boys were killed and three other teens were injured in Gaza on Friday from an unexploded Israeli ordnance , Palestinian medical and security officials said . Hamas security sources say the explosive device was left over from Israel 's 22-day Gaza offensive that began two years ago . There was no immediate Israeli response to this incident . The Palestinian sources also reported the wounding of two people in Gaza , one a worker collecting gravel near the Erez Crossing and another a farmer east of Khan Younis . An Israel Defense Forces spokesman said Israeli forces fired shots when suspicious people approached the fence between Gaza and Israel in two separate locations . One incident occurred in northern Gaza and the other took place near Khan Younis . Troops first fired warning shots in the air but the people continued moving . Then , they fired at their legs , the IDF said .
The device was left over from the Gaza offensive . In other incidents , two people were wounded .