PHILADELPHIA (WPVI) -- Authorities confirm an off-duty Philadelphia police officer was killed when his vehicle crashed into a tree this past weekend.The officer has been identified as 38-year-old Alexis Montanez.Montanez was a 17-year veteran of the force and assigned to the 9th Police District, officials said.It happened around 3:30 a.m. Saturday on the 2900 block of Holme Avenue in Northeast Philadelphia.Police said Montanez was driving westbound when he lost control of his 2007 Infiniti and crashed into a tree.Medics pronounced him dead at the scene.There is no information at this time on why Montanez lost control of the vehicle.