I know of two accidents where people were injured by lightning on the ramp. One happened a few years ago with my previous employer. A former colleague, who was in the process of dispatching an aeroplane and thus on the headset got struck when lightning hit close by (fortunately not the aircraft he was connected with, the jolt was strong enough to collapse him like a poleaxed ox, he was out for several minutes, but recovered fast).
This summer, at the airport I'm currently working at, a ramper got struck by lightning while operating a main deck loader. His manager insisted on the loading crew to continue loading a plane to catch up on a delay, even though a thuderstorm was directly overhead and he was breaking health and safety rules (The unions and health and safety board had a field day with this incident).
The ramper was brought to hospital by ambulance, but recovred after a few days.
For me as maintenance shift leader, I will not have any of my mechanics and engineers outside if there is a thunderstorm within 5 miles of the airport. Neither will the ground handling provider (if they obey the rules). It is simply too dangerous. Imagine you are soaked, in streaming rain, on a wet concrete surface , electrically connected to a metal object with a pointy fin sticking up into the air.