NIRIM, Israel, May 21 (Reuters) - Israeli troops killed two armed Palestinians who crossed into Israel on Friday from the Hamas-controlled Gaza Strip, a military spokeswoman said.

They entered Israel near Nirim, a small farming community, after breaching the security fence along the border with the Palestinian enclave, she said.

The soldiers on the scene and the gunmen exchanged fire, during which both gunmen were killed, the spokeswoman said. No Israelis were hurt in the incident. Israeli media said soldiers ordered residents of Nirim to stay indoors during the gunfight.

No group in the Gaza Strip claimed responsibility for the incident.

Hamas has been urging smaller militant groups to refrain from launching attacks against Israel, which carried out a devastating military offensive in the Gaza Strip 17 months ago with the aim of halting cross-border rocket fire.

Israeli air strikes targeted tunnels in the northern and southern Gaza Strip early on Friday after Palestinian militants fired two rockets that landed in fields inside Israel.

The Israeli army says that some 350 rockets have been fired from the Gaza Strip since Israel ended its military offensive there in January 2009.

More than 3,000 rockets and mortar rounds were fired at Israel from the Gaza Strip in 2008. (Reporting by Nidal al-Mughrabi and Joseph Nasr; writing by Joseph Nasr, editing by Tim Pearce)