Insanely scary moment on the MLB diamond Wednesday ... Reds star rookie Jonathan Indiawas drilled in the forehead by a 94 MPH fastball, but thankfully, he appears to be okay.

India was at the dish for his second at-bat of Cincinnati's game against the Pirates ... when pitcher Chad Kuhl lost control of a fastball and accidentally plunked the 24-year-old in the head.

India immediately crumpled to the ground in pain...