A child’s birthday party was interrupted today by a sudden spring storm in Paris, which caused 11 people, including eight children, to be stuck by lightning.

USA Today reports the group was celebrating at Parc Monceau, a popular hangout for wealthy families in the area, when the storm suddenly rolled in and forced them to seek shelter under a nearby tree.

Six of the 11 hit by lightning were seriously injured, including four children and two adults, spokesman Eric Moulin said. Five only suffered minor injuries while four were in life threatening condition. At the time of publication no one has died from the event.

There was an off-duty fireman on the scene who may have saved several lives. He saw the group huddled under the tree and rushed over to bring them to a more secure and safe location.

Moulin says, “without his actions, it would have been much worse.”

The storm continued into Germany where more were struck, according to the BBC. It hit a children’s football match in Hoppstaedten, injuring an additional 35 people.

Lightning flashes near Christ the Redeemer statue (Lower C, Illuminated) and the Cantagalo favela community (Lower R) on February 23, 2016 in Rio de Janeiro, Brazil.

Lightning is attracted to tall objects in the area so hiding under a tree is one of the most unsafe areas to be during a lightning storm. Of course, indoors is the best place be during a lightning storm, but when caught outside the Centers for Disease Control and Prevention recommends getting in a car or squatting in an area away from tall objects, metal, or concrete. Don’t lay down, because the shock reverberates through the ground and can be deadly up to 100 feet away from the place of initial strike.

Even indoors it can be dangerous. The CDC says one third of all lightning strike injuries occur inside. The center recommends avoiding water lines, electrical equipment, metal, and concrete floors.

Thankfully there was a firefighter on hand who was aware of some of these precautions and could help the children, who are reported to be around nine years of age.