You would need much more water than you average fire truck can pump to stop those engines - they are huge.....?
Trent 500 is certified to continue running without flameout in all conditions at a water flow of 1,200l/min.
Oshkosh 4500 (4,500 gall capacity) airport firetender can deliver water at 4,500 l/min. Should be enough me thinks.
Trent 500 fan diameter about 1.6m, thrust 56,000lbs. GE90-115B 115,300lbs, 3.5m
JFGI - just flippin' google it.....