Alert comes after two Palestinian teens said killed during violent protests along Gaza border and Hamas vows revenge

At least two Palestinian men seen holding what appear to be guns in surveillance video from Saturday night border incident

Suspected infiltration attempt comes hours after three rockets fired at southern Israel from the Strip, one of which struck a home in Sderot

No reports of injury or damage as projectile apparently fired at Israeli communities

Reports say at least two rockets fired into Israel, intercepted by Iron Dome; IDF investigating

Activation of warning systems comes after pair of projectiles were fired at Israel Friday evening; Egyptian security delegation said to leave Strip after meeting with Hamas leaders

Alarm comes amid relative calm along the border following reported ceasefire; earlier, Hamas fires rocket into sea in test

IDF investigating; no indication of what tripped warning system in Moshav Dishon, adjacent to Lebanese border

Alarms based on individual towns -- or neighborhoods, in some cases -- as opposed to old system that operated based on larger regions

Sirens to sound in individual towns, as opposed to old system that operated based on larger regions; army says test unrelated to Iran tensions