A lightning strike in Washington, D.C. Thursday night sent four people to the hospital in critical condition.
"It appeared they were in the vicinity of a tree," said Vito Maggiolo, a spokesman for the District of Columbia Fire and Emergency Medical Services Department, during a news conference.
The lightning strike happened at Lafayette Square, a park just north of the White House.
"All we know for sure is that there was a lightning strike in their immediate vicinity and all four were injured," said Maggiolo.
The victims -- two men and two women -- were found unconscious at the scene and taken to the hospital with life-threatening injuries.
Secret Service and US Park Police officers in the area saw the strike happen and immediately began providing assistance to the victims.
"Their agents, their officers, witnessed this lightning strike and immediately began to render aid," Maggiolo said.
The National Weather Service (NWS) had issued a severe thunderstorm warning for the DC area Thursday evening.
"This is NOT a joking matter," tweeted weather analyst Chris Vagasky. "9 people have been killed by #lightning this year in the US. 4 people were struck in DC today and are in critical condition."