  Surveys with James Webb Space Telescope (JWST) have discovered candidate
galaxies in the first 400 Myr of cosmic time. Preliminary indications have
suggested these candidate galaxies may be more massive and abundant than
previously thought. However, without confirmed distances, their inferred
properties remain uncertain. Here we identify four galaxies located in the JWST
Advanced Deep Extragalactic Survey (JADES) Near-Infrared Camera (NIRCam)
imaging with photometric redshifts z~10-13. These galaxies include the first
redshift z>12 systems discovered with distances spectroscopically confirmed by
JWST in a companion paper. Using stellar population modelling, we find the
galaxies typically contain a hundred million solar masses in stars, in stellar
populations that are less than one hundred million years old. The moderate star
formation rates and compact sizes suggest elevated star formation rate surface
densities, a key indicator of their formation pathways. Taken together, these
measurements show that the first galaxies contributing to cosmic reionisation
formed rapidly and with intense internal radiation fields.
