Israel announced Thursday that the military killed three Palestinians who tried to infiltrate Israel in northern Gaza Strip.

Palestinian sources also confirmed that the Israeli military killed three people, but denied they approached a security fence separating Gaza and Israel.

Adham Abu Selmia, a spokesman for Palestinian medical emergencies, said that ambulance crews evacuated the bodies of the three to the west of Beit Lahiya town in northern Gaza Strip.

Residents said the slain were young men working in digging gravel from a former settlement in northern Gaza that Israel had evacuated in 2005.

Witnesses said they heard the sound of heavy machine gun shooting from northern Gaza's borders with Israel, adding that a helicopter gunship participated in the operation to kill the three.

Israel has allocated a 300-meter-wide buffer zone along its borders with northern and eastern Gaza Strip, saying it aims to distance militants from its troops and watchtowers.

Thursday's incident puts the death toll of civilians killed since February 2010 in the no-go area to five.