The first observation of exotic states with a new quark content c ¯ c u ¯ s decaying to the J / ψ K + final state is reported with high significance from an amplitude analysis of the B + → J / ψ ϕ K + decay. The analysis is carried out using proton-proton collision data corresponding to a total integrated luminosity of 9 fb − 1 collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. The most significant state, Z c s ( 4000 ) + , has a mass of 4003 ± 6 + 4 − 14 MeV , a width of 131 ± 15 ± 26 MeV , and spin parity J P = 1 + , where the quoted uncertainties are statistical and systematic, respectively. A new 1 + X ( 4685 ) state decaying to the J / ψ ϕ final state is also observed with high significance. In addition, the four previously reported J / ψ ϕ states are confirmed and two more exotic states, Z c s ( 4220 ) + and X ( 4630 ) , are observed with significance exceeding 5 standard deviations.