  Markarian 421 is the nearest high-energy peaked blazar and also is the first
extragalactic source to be detected in multi-TeV $\gamma$-rays. It has been
observed in multiwavelength for exceptionally long period of time with dense
monitoring and several major outbursts have been detected from this source. In
March 2010, the source was in a high state of activity and was observed in
multiwavelength by various telescopes for 13 consecutive days. During this
period the position of the synchrotron peak was found to be above $10^{17}$ Hz
and also the position of the second peak was shifted towards higher energy, a
signature of extreme HBL-like behavior. We observed that the standard
photohadronic model is inadequate to explain the observed spectra. However, a
recently proposed two-zone photohadronic model explains very well the GeV-TeV
flaring events observed by both MAGIC and VERITAS telescopes. From the
observation of the highest energy $\gamma$-ray event on MJD 55266 we also
estimated the minimum bulk Lorentz factor.
