  Observing and understanding the origin of the very-high-energy (VHE) spectral
component in gamma-ray bursts (GRBs) has been challenging because of the lack
of sensitivity in MeV-GeV observations, so far. The majestic GRB 221009A, known
as the brightest of all times (BOAT), offers a unique opportunity to identify
spectral components during the prompt and early afterglow phases and probe
their origin. Analyzing simultaneous observations spanning from keV to TeV
energies, we identified two distinct spectral components during the initial 20
minutes of the burst. The second spectral component peaks between $10-300$ GeV,
and the bolometric fluence (10 MeV-10 TeV) is estimated to be greater than
2$\times10^{-3}$ erg/ cm$^{2}$. Performing broad-band spectral modeling, we
provide constraints on the magnetic field and the energies of electrons
accelerated in the external relativistic shock. We interpret the VHE component
as an afterglow emission that is affected by luminous prompt MeV radiation at
early times.
