  Recent LHCb experiments have shown us that there are two resonances in the
$J/\psi p$ channel in the $\Lambda_b$ decay, whose spin and parity are most
probably (3/2$^-$ 5/2$^+$). In this work, we investigate the
$I(J^P)=1/2(1/2^-)$, $1/2(3/2^-)$, and $1/2(5/2^-)$ $uudc{\bar c}$ pentaquark
states by employing the quark cluster model. It is found that the color-octet
isospin-1/2 spin-3/2 $uud$ configuration gives an attraction to such five-quark
systems. This configuration together with the color-octet $c{\bar c}$ pair
gives structures around the $\Sigma_c^{(*)}{\bar D}{}^{(*)}$ thresholds: one
bound state, two resonances, and one large cusp are found in the $uudc{\bar c}$
negative parity channels. We argue that these resonances and cusp may
correspond to, or combine to form, the negative parity pentaquark peak observed
by LHCb.
