Four homicides occurred on the Metro system in 2012, even as jurisdictions around the region celebrated massive reductions in the number of slayings.

The transit agency had three people slain on its bus system, including 20-year-old Selina Brown as she held her toddler in her arms last month. And 18-year-old Olijawon Griffin was fatally stabbed in the Woodley Park Metro station on Nov. 17, apparently over his jacket and cellphone.

The number of homicides is unusually high for the transit agency, which had four cases in the past five years combined. Homicides are so rare on the system that Metro turns over the cases to police in the local jurisdiction, such as the Metropolitan Police Department if they occur in the District. Three of the four cases occurred in the District last year, and one happened in Prince George's County.

The surge in slayings last year is especially striking given the declines in homicides elsewhere around the region. The District had 88 homicides all year, the lowest number on record since 1961, a feat celebrated by Mayor Vincent Gray and Police Chief Cathy Lanier on Thursday. Prince George's County logged fewer cases than it had in years, too.

Homicides on Metro
2012: 4
2011: 1
2010: 1
2009: 1
2008: 0
2007: 1
2006: 2
2005: 0

To be sure, Metro's numbers are small enough that two deadly shootings can double the homicide statistics. And the angle of a single bullet -- or the care received in an emergency room -- can make the difference between a death and an "aggravated assault."

"Because we're talking about such low numbers, the percentage change would not be meaningful," said Metro spokesman Philip Stewart.

Metro has repeatedly noted that its crime rate is low for the hundreds of thousands of people who use the system each day. Total crimes and the annual rate on the system for 2012 were not available Thursday.

But life happens on Metro. In 2012 alone, a woman went into labor, while a newborn died a natural death on the train system. A domestic dispute spilled onto the bus system in the death of Selina Brown, leaving a toddler with both parents dead and a bullet wound on her face.

Metro has not always been forthcoming about its homicides. In 2011 and 2010, it did not include any homicides in its annual crime statistics, only adding them after The Washington Examiner asked questions about their absence. The agency has said that the cases were not included because the Metro Transit Police did not lead the investigations. The agency later added them with an asterisk.

Similarly, Metro did not list in its latest scorecard covering statistics through September a fatal shooting at the Southern Avenue Metro bus bay from June 5 that left 43-year-old Harold T. Detter, of Temple Hills, dead. It also did not list the fatal stabbing of JaParker Jones, also known as Deoni, who was attacked at a Metrobus stop on the 4900 block of East Capitol Street in Northeast D.C. on Feb. 2. For those months, Metro listed zero homicides.