My Vauxhall Vectra 2.0 yr2000 has dumped all its coolant ?

I have a 2.0 Vauxhall Vectra yr 2000 122K miles,
I drove it to the shops this morning, on the way it sounded lie something was wrong. When i got back in to drive home, 600metres, the low coolant light came on. The scraping got worse, and coolant was just beig duped all over the road. As i was pulling ontthe drive, the engine died and cannot be restarted. all the remaining coolant dumped.

Does anyone have an idea what might of one wrong?