Police said 76-year-old James Mueller and 75-year-old Donna Meuller died after being injured in the strike in Lafayette Park.
WASHINGTON -- A third person has died following a lightning strike near the White House on Thursday night, police confirmed to ABC News Friday.
Two Wisconsin residents are among the victims. The third person has not yet been identified, pending notification of next of kin, officials said.
Police said 76-year-old James Mueller and 75-year-old Donna Meuller, both from Janesville, Wisconsin, died after being injured in the strike in Lafayette Park in front of the White House.
Thursday night, D.C. Fire and EMS said it had responded and was treating four patients that were found in "the vicinity of a tree."
It said the two men and two women were transported to area hospitals with "life-threatening injuries."
The fourth victim, an adult female, is still in critical condition and being treated, according to MPD.
Officials said it's still unclear what the adults were doing prior to the lightning strike, if they knew each other and why they were in the park.
Uniformed U.S. Park Police officers and members of the Secret Service were also on the scene and immediately rendered aid to the victims, an EMS official said during a news conference.
The National Weather Service had issued a severe thunderstorm warning for the area Thursday evening.
The Mueller were in D.C. to celebrate their 56th wedding anniversary. The couple was high school sweethearts.
ABC News' Beatrice Peterson and ABC7 Chicago contributed to this report.