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Baltimore's second attempt at a 72-hour cease-fire was cut short after midnight Saturday when police say an off-duty officer was fatally shot.

Metropolitan police Sgt. Tony Mason Jr. was struck inside a parked vehicle in Baltimore and was transported to a nearby hospital, where he later died from his wounds, police said.

#BaltimoreCeasefire Let’s pray 4 peace this weekend. pic.twitter.com/0ofLCXOFXP — Living in the Cross (@dougevaughn) November 4, 2017

Mason was a 17-year veteran of Washington's Metropolitan Police Department. A woman who was with Mason at the time of the shooting was also hit in the leg, but is expected to recover.

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Baltimore police said they have launched an investigation into the shooting and the shooter remains unknown.

On Friday, Baltimore hit 300 homicides in 2017, according to police data, making this the third year in a row that the city has reached the grim milestone.

Related: Baltimore Activists Hold Second Cease-Fire as City Reaches 300 Homicides

Saturday’s shooting occurred just 26 hours after the community activists launched a three-day cease-fire aimed at curbing the relentless pace of the city’s murder rate.

Local activist Erricka Bridgeford created the organization Baltimore Ceasefire and helped organize events and activities throughout the city in an effort to call for peace.

She said the group now plans to visit the site where Mason was shot and pay their respects.

In August, Bridgeford's first attempt to call for a 72-hour cease-fire ended early when two men were killed within hours of one another.

According to The Baltimore Sun, more than 90 percent of the homicides in Baltimore are a result of shootings, and more than 90 percent of the victims have been black boys and black men between the ages of 18 and 30.