  A search for first generation scalar and vector leptoquarks produced in ep
collisions is performed by the H1 experiment at HERA. The full H1 data sample
is used in the analysis, corresponding to an integrated luminosity of 446
pb^-1. No evidence for the production of leptoquarks is observed in final
states with a large transverse momentum electron or with large missing
transverse momentum, and constraints on leptoquark models are derived. For
leptoquark couplings of electromagnetic strength lambda=0.3, first generation
leptoquarks with masses up to 800 GeV are excluded at 95% confidence level.
