  We present JWST/NIRSpec prism spectroscopy of seven galaxies selected from
the Cosmic Evolution Early Release Science Survey (CEERS) NIRCam imaging with
photometric redshifts z_phot>8. We measure emission line redshifts of z=7.65
and 8.64 for two galaxies, and z=9.77(+0.37,-0.29) and 10.01(+0.14,-0.19) for
two others via the detection of continuum breaks consistent with Lyman-alpha
opacity from a mostly neutral intergalactic medium. The presence (absense) of
strong breaks (strong emission lines) give high confidence that these two
galaxies are at z>9.6, but the break-derived redshifts have large uncertainties
given the low spectral resolution and relatively low signal-to-noise of the
CEERS NIRSpec prism data. The two z~10 sources are relatively luminous
(M_UV<-20), with blue continua (-2.3<beta<-1.9) and low dust attenuation
(A_V=0.15(+0.3,-0.1)); and at least one of them has high stellar mass for a
galaxy at that redshift (log(M_*/M_sol)=9.3(+0.2,-0.3)). Considered together
with spectroscopic observations of other CEERS NIRCam-selected high-z galaxy
candidates in the literature, we find a high rate of redshift confirmation and
low rate of confirmed interlopers (8.3%). Ten out of 34 z>8 candidates with
CEERS NIRSpec spectroscopy do not have secure redshifts, but the absence of
emission lines in their spectra is consistent with redshifts z>9.6. We find
that z>8 photometric redshifts are generally in agreement (within
uncertainties) with the spectroscopic values. However, the photometric
redshifts tend to be slightly overestimated (average Delta(z)=0.50+/-0.12),
suggesting that current templates do not fully describe the spectra of very
high-z sources. Overall, our results solidifies photometric evidence for a high
space density of bright galaxies at z>8 compared to theoretical model
predictions, and further disfavors an accelerated decline in the integrated UV
luminosity density at z>8.
