  The radiation mechanism of very high energy $\gamma$-ray emission from
blazars and crucial parameters like magnetic field, and size of the emitting
region are not well understood yet. To understand the above mentioned
properties of blazars, we observed five nearby TeV $\gamma$-ray emitting
blazars (Mrk421, Mrk501, 1ES2344+514, 1ES1218+304 and 3C454.3) and one radio
galaxy (M87) using the High Altitude GAmma Ray (HAGAR) telescope. HAGAR is an
array of seven telescopes located at Hanle, India to detect Cherenkov light
caused by extensive air showers initiated by $\gamma$-rays. Mrk421 was observed
to undergo one of its brightest flaring episodes on 2010 February 17, and
detected by various experiments in X-rays and $\gamma$- rays. HAGAR
observations of this source during 2010 February 13 - 19, in the energies above
250 GeV show an enhancement in the flux level, with a flux of 6-7 Crab units
being detected on 2010 February 17. We present the spectral energy distribution
of the source during this flaring episode. In addition to this, the analysis
procedure to extract $\gamma$-ray signal from HAGAR data is discussed and
preliminary results on all the AGNs are presented.
