A section mill for removing a portion of a casing in a wellbore. The section mill may include a body having a first end portion, a second end portion, and a bore formed axially therethrough. A plurality of blades may be coupled to the body. Each of the blades may have a first end portion and a second end portion. The first end portion of each blade may be coupled to the body via a hinge pin, and the second end portion of each blade may have a cutting surface formed thereon. A seat may be formed within the bore. The blades may be adapted to actuate from an inactive position to an active position in response to an impediment forming a seal against the seat.