The physical mechanism at the origin of gamma-ray bursts (GRBs) is far from being completely
understood. Describing their emission up to very high energies (GeV-TeV) is one of the most
challenging and important tasks needed to unveil the physics of these peculiar events. Using
data collected by the HAWC gamma-ray observatory, we search for TeV emission coming from
a sample of GRBs detected by Fermi and Swift between December 2014 and May 2017. We
derive upper limit over different time intervals and use them to constrain the micro-physical pa-
rameters and the bulk Lorentz factor under the assumption of Self-Synchrotron Compton within
the external shock model scenario. We present the results of this analysis discussing possible
interpretations.