From Reuters:

GAZA (Reuters) – A spokesman for gunmen in the Gaza Strip said they had fired a rocket tipped with a chemical warhead at Israel early on Thursday.
The Israeli army had no immediate comment on the claim by the spokesman from the al-Aqsa Martyrs Brigades, an armed wing of Palestinian President Mahmoud Abbas’s Fatah movement.
The group had recently claimed to possess about 20 biological warheads for the makeshift rockets commonly fired from Gaza at Israeli towns. This was the first time the group had claimed firing such a rocket.