* Rockets hit Israel's Sderot, no injuries reported - police
* Army strike hits Hamas camps, two wounded - sources
* No initial comment from smaller Islamist groups in Gaza (Updates number of rockets, adds Israeli retaliation)
GAZA, April 21 (Reuters) - Seven rockets fired from the Gaza Strip landed in southern Israel during the Jewish Passover holiday on Monday, drawing retaliatory air strikes from the Israeli army, officials said, the first cross-border clash in several weeks.
Israel's army said its strikes hit two training camps run by Hamas, the Palestinian Islamist group that controls Gaza. Medical sources there said two Hamas militants were lightly wounded.
Hamas has largely maintained a truce with Israel since a brief war in late 2012, but it has sometimes struggled to rein in smaller armed Islamist factions hostile to the Israel.
There was no claim of responsibility for the latest rocket salvo from any of those factions, who are opposed to troubled peace talks between their Palestinian rivals in the occupied West Bank and Israel.
Two of the projectiles from Gaza exploded in the southern Israeli border community of Sderot in a road and an open area, Israeli police said. There were no reports of any injuries.
Israel holds Hamas responsible for any rocket fire from the Strip and routinely retaliates against it.
"Israeli civilians celebrating the Passover Holiday woke up this morning to the sound of Code-Red alarms and rockets ... Hamas rocket terrorism is an intolerable reality Israelis should not have to accept," Israeli army spokesman Peter Lerner said in a statement.
Residents of Beit Hanoun in northern Gaza said an Israeli helicopter opened fire there, though it was not clear what it was targeting. Hamas confirmed its training camps had been attacked but did not comment on the reports of rockets.
Israel withdrew from Gaza in 2005 after 38 years of occupation, a unilateral move that boosted Hamas, Islamic Jihad and other Palestinian groups.
Palestinians seek a state in the West Bank and Gaza, with East Jerusalem as its capital.
Two Islamist groups fired rockets at Israel over several days in early March, and Israel responded with air strikes. (Reporting By Noah Browning and Nidal al-Mughrabi; Editing by Andrew Heavens)