The four women had sought shelter in a wooden cabin when a heavy electrical storm broke as they played a round of golf at Waldeck golf course in North Rhine-Westphalia, according to police.
At around 5pm, the cabin roof and a nearby tree were both struck - three of the women were killed instantly, while the fourth was airlifted to hospital in Kessel by helicopter with life-threatening injuries.
The four women, aged 41, 50, 66 and 67 had been on the seventh hole when the storm broke over head. The women took shelter under the wooden hut, which unfortunately was in an exposed position on one of the highest parts of the golf course.
It was an understandable mistake to shelter there, said police spokesman Jörg Virnich. The wisest thing would have for the women to run down in into the valley and turn off their mobile phones, which can act as conductor for the lightning.
Not far away, their husbands had been playing on another course and had to watch as the tragedy unfolded - it was they who alerted the emergency services, said Virnich.
Weather services had issued storm warnings on Friday for several regions in the area and a 32-year-old construction worker was also taken to hospital after being struck by lightning.