  We report on the likely detection of gamma-ray emission from the supernova
remnant (SNR) Kesteven 27 (Kes 27). We analyze 5.7 yr Fermi Large Area
Telescope data of the SNR region and find an unresolved source at a position
consistent with the radio brightness peak and the X-ray knot of Kes 27, which
is located in the eastern region of the SNR and caused by the interaction with
a nearby HI cloud. The source's emission is best fit with a power-law spectrum
with a photon index of 2.5 +/- 0.1 and a >0.2 GeV luminosity of 5.8*10^34 erg
s^-1 assuming a distance of 4.3 kpc, as derived from radio observations of the
nearby HI cloud. Comparing the properties of the source with that of other SNRs
that are known to be interacting with nearby high-density clouds, we discuss
the origin of the source's emission. The spectral energy distribution of the
source can be described by a hadronic model that considers the interaction of
energetic protons, escaping from the shock front of Kes 27, with a high-density
cloud.
