  Hypervelocity stars are believed to be ejected out from the Galactic center
through dynamical interactions of (binary) stars with the central massive black
hole(s). In this letter, we report 13 metal-poor F-type hypervelocity star
candidates selected from 370,000 stars of the data release 7 of the Sloan
Digital Sky Survey. With a detailed analysis of the kinematics of these stars,
we find that seven of them were likely ejected from the Galactic center (GC) or
the Galactic disk, four neither originated from the GC nor the Galactic disk,
and the other two were possibly ejected from either the Galactic disk or other
regions. Those candidates which unlikely originated from the GC or the Galactic
disk, may be explained by other mechanisms, like the tidal disruption of the
Milky Way's dwarf galaxies in the Galactic potential, or the gravitational
interactions with a massive black hole at the center of M31 or M32.
