Israeli troops killed four Palestinian gunmen early Monday in a flare-up of violence along the tense frontier between Israel and Hamas-controlled Gaza, a Palestinian official said.

A group of around 10 gunmen were trying to cross the border fence into Israel when they were spotted by troops, according to Palestinian security officials. Dr. Moaiya Hassanain of the Gaza Health Ministry said four fighters were killed in the clash.

The Israeli military said soldiers patrolling the fence early Monday came under fire and shot back. There were no reports of Israeli casualties.

Gaza has been relatively quiet since Israel ended its devastating three-week offensive against Hamas in January, but sporadic violence has continued along the border.

Most of those incidents, including attacks against Israeli patrols and bombs planted along the fence, have been initiated by small militant groups and not by Hamas, the Islamic organization which has controlled Gaza for two years. Hamas may be trying to avoid drawing another Israeli incursion such as the one sparked early this year by militant rocket fire at Israeli towns.

That offensive left more than 1,400 Palestinians dead, including more than 900 civilians, according to Palestinian officials and human rights groups. It also destroyed thousands of homes and heavily damaged Gaza's infrastructure.

Israel says most of the dead were armed militants.