Suddenly a strong earthquake shook the foundations of the prison. At once all the doors flew open and everyone’s chains came loose.
KJV
And suddenly there was a great earthquake, so that the foundations of the prison were shaken: and immediately all the doors were opened, and every one’s bands were loosed.
ASV
and suddenly there was a great earthquake, so that the foundations of the prison-house were shaken: and immediately all the doors were opened: and every one’s bands were loosed.