PARIS (Web Desk) – As many as eight children and three adults in Paris were struck by lightning on Saturday after a sudden spring storm sent bolts crashing down on a children’s birthday party in a city park, a fire official said.

The victims had sought shelter under a tree at Park Monceau, a popular weekend hangout for well-to-do families in Paris, CBS news reported.

Paris fire service spokesman Eric Moulin said six of those hit were seriously injured, including four children and two adults, while four were left in life-threatening condition. He said five others had been slightly injured by the lightning, including four children.

An off-duty fireman visiting a nearby museum ran immediately to the scene and saw nine of the 11 victims lying on the ground under the tree, Moulin told The Associated Press. The fireman who arrived at the scene administered first aid, including heart massages, and helped direct rescuers to the scene, he added.

“He saw who was the most seriously wounded. He did a quick triage of the victims. He did first aid. He alerted the rescue services,” Moulin said. “Without his actions, it would have been much worse.”

Moulin said all the children hit by lightning were around 9 years old. One Paris resident who lives near the park and saw the lightning crashing down said it was rare to see such a wild storm hitting the French capital.

“It was dramatic,” said resident Jean-Louis Laurens.