1994 Nissan Truck Shocks are Locked in the Extended Positio

Suspension problem
1994 Nissan Truck 4 cyl Two Wheel Drive Manual 180k miles

I went over a large bump yesterday, and my rear shocks locked up in the fully extended position. The whole rear end is now way up in the air and very stiff.

Do these shocks need to be replaced? Could this be a symptom of more serious damage?

Thank you for your help.