Since February 1997 the BL Lac object Mkn 501 is in a “ high state ” of \gamma -ray emission .
The HEGRA collaboration has studied Mkn 501 with their air Čerenkov telescopes on La Palma .
Here we report on observations with the 5 m ^ { 2 } telescope ( threshold \approx 1.5 TeV ) operated in a stand alone mode .
We observed a rapidly varying flux between 0.5 to 6 times of that from the Crab Nebula .
On average a Mkn 501 flux of ( 2 + 1.3 - 0.5 ) \times 10 ^ { -11 } \mathrm { cm } ^ { -2 } \mathrm { s } ^ { -1 } has been determined .
The spectrum extends at least up to 10 TeV with an integral power law coefficient of 1.8 \pm 0.2 and seems to be steeper than in 1996 .