GAZA, July 5 (Reuters) - The Israeli air force fired into the Gaza Strip on Tuesday, killing two gunmen from an al-Qaeda-affiliated Palestinian faction who approached the boundary fence, medical officials and militant sources said.

The two dead and a comrade wounded in the strike belonged to the Tawheed and Jihad group, radical Islamists who have challenged Hamas rule over the Palestinian enclave, militant sources said.

The Israeli military said in a statement its air force had attacked a squad of terrorists preparing to launch rockets across the frontier.

In a separate incident, Palestinian gunmen fired through the fence at an Israeli military vehicle, lightly wounding the driver, the statement said.

Gaza, scene of fierce fighting between Hamas and Israel in the past, had been relatively quiet as the ruling Islamist group hammered out a power-sharing accord signed in April with its U.S.-backed, West Bank-based rival, the Palestinian Authority.

But the Israeli military statement said three rockets had been launched from Gaza this week. There were no casualties or damage from those incidents.

(Reporting by Nidal al-Mughrabi; Writing by Dan Williams; Editing by Peter Cooney)