You probably triggered the safety valve in the tank supply valve .
Turn the tank valve off , make sure all appliances are off .
Open the tank valve painfully slowly . Safety valve will trip if there is no back pressure in the system; so you need to allow back pressure to build before fully opening the valve.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.