Serious crime increased last year across the Metro transit system by 12 percent, fueled by surging numbers of aggravated assaults and robberies by thieves who snatch smartphones, MP3 players and other electronic devices from rail passengers and flee, Metro has reported.

The bus and rail system serving Maryland, Virginia and the District reported 2,279 serious crimes in 2010. That marks a five-year high from 2006, when 1,440 incidences were reported.

From 2009 to 2010, the number of rapes and sexual offenses grew from one to seven; four of the sexual offenses allegedly involved assaults on disabled customers by MetroAccess drivers.

The largest single increase was in aggravated assaults, from 94 to 136. Metro officials said a third of those altercations involved its own bus drivers, some of whom had confrontations with passengers who refused to pay fares.

The other big increase came in "snatch" robberies, from 425 to 508. The rise was fueled by a booming market in MP3 players and smartphones, creating opportunities for fleet-footed thieves who often grab the devices as train doors close. Overall, robberies, including electronics thefts, increased from 398 in 2006 ago to 1,007 last year.

The four Metro stations with the most incidents of crime were New Carrollton, Branch Avenue, Greenbelt and Prince George's Plaza, all in Prince George's County.

The Metro crime data, in a security report to be presented to Metro's board of directors Thursday, were first reported by the Washington Examiner.

The electronics thefts, following a nationwide trend among big-city transit systems, became so prevalent that Metro Transit Police began to deploy "robbery suppression teams" in which plainclothes officers display fake iPods and other devices in an effort to entice would-be robbers, Transit Police Deputy Chief Ronald Pavlik said. The teams have made dozens of arrests in the past year.

"It's a trend we are seeing in other transit agencies across the United States, and it's geared toward electronic devices," Pavlik said.

A thief struck Jennifer Schell so fast that she was left in shock, her iPod buds still in her ears and a dangling wire left where the device should have been.

Schell was sitting in an aisle seat on a packed Red Line train as she headed home from work, reading a book that covered the purse containing her iPod. As the train pulled into the Fort Totten Station, a young man walked past. In an instant, he slipped his hand into her purse and snatched the $200 device.

"With a flick of his wrist, he snapped the iPod free from the buds . . . and walked off" with it, said Schell, 26, of the District. "I got off the train and yelled, but there was no capturing him," she said. "It was a surreal moment."