In Ukraine's volatile east, a day of shelling, outages, fear

Shells struck by the hundreds along the tense front lines in eastern Ukraine

KYIV, Ukraine -- Shells struck by the hundreds along the tense front lines in eastern Ukraine, drones monitoring a fragile cease-fire lost their way when the GPS signal they rely on was jammed, and then the cellphone network went dark.

In a sliver of land where pro-Russian separatists have battled for years against Ukrainian government forces, a group of international monitors tasked with keeping the peace reported more than 500 explosions in the the 24 hours ending Thursday midday, around four times as many as an average day over the past month.

As the world warily watches Russian troops massing near Ukraine's borders for signs they're preparing to invade, Western officials have warned that the spark could come from the volatile east: Repeatedly in recent weeks, the U.S. has said the simmering conflict there could provide cover or an excuse for Russia to roll across the border.

The number of explosions eased as the day went on, but by then the village of Stanytsia had already suffered more than its share. One shell crashed into a kindergarten, blasting a hole in the wall that sent soccer balls flying off the classroom shelves just as the school day started. Others blasted craters into the schoolyard and shattered windows of nearby homes.