Take a helicopter, hang a cargo net at least 300 feet or more below the helicopter.
Weight down the corners of the cargo net so it hangs vertically. Fly the net in front of the balloon and let the balloon come to the net and get trapped in the net.
Then lower the net and helicopter to the ground.
Remember, at LA California, the rotor wash will blast down at least 175 feet(the man who took the lawn chair ride suspended with balloons).
Also hook a man into the cargo net with a radio to talk to the pilot to direct the alignment of the net to catch the balloon.