Terrifying scene in Michigan — a helicopter took a tumble and in a catastrophic crash … right next to a lakefront restaurant, and the whole thing was caught on camera by stunned diners.

Watch this — as the chopper tried to touch down on the beach at Lake St. Clair, it suddenly tipped forward, skidded forward on its blade, then violently crashed onto its side … sending up a massive cloud of smoke and dirt.

There was total panic at Cabana Blue Lakefront Sports Bar & Grill — diners sprinted from their seats to the wreckage, trying to help the chopper’s passengers after the horrifying crash.

Miraculously, all 4 people onboard walked away without a scratch — no injuries were reported.