Israeli police say Hamas militants have fired a phosphorus shell from Gaza into Israel for the first time since war broke out Dec. 27.
Police spokesman Micky Rosenfeld says the mortar shell exploded in a field near the border town of Sderot Wednesday evening. There were no casualties.
Human Rights Watch says Israel has used phosphorous shells, which illuminate targets at night or create a smoke screen for day attacks.
Phosphorus shells can burn anything they touch and pose a threat to non-combatants if used in civilian areas. Israeli says it uses munitions in line with international law.