High-resolution atomic-beam laser spectroscopy in Eu I has been performed using a tunable diode laser. The hyperfine structure (hfs) and isotope shift of the 4f(7)6s(2) S-8(7/2)-4f(7)6s6p P-10(9/2) transition at 686.45 nm have been measured. The hfs constants A and B of Eu-151 and Eu-153 have been determined for the upper state 4f(7)6s6p P-10(9/2), and the hyperfine anomaly has been derived. The DeltaF = +2 transitions, normally forbidden, have been induced by applying a magnetic field of approximately 1 G. Their intensity dependences on the magnetic field strength and on the hfs splittings agreed with the first-order perturbation theory, which considers the mixing between the closely lying hfs levels in the ground state.