Two Wisconsin residents celebrating their wedding anniversary died following a lightning strike near the White House on Thursday night, police confirmed to ABC News Friday.

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4 people injured by lightning strike near White House
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A third victim -- a 29-year-old man -- has also died in the incident, police said Friday afternoon. A fourth person is still in critical condition following the lightning strike, police said.

Police said 76-year-old James Mueller and 75-year-old Donna Mueller, both from Janesville, Wisconsin, died after being injured in the strike in Lafayette Park in front of the White House.

Metropolitan Police Department Chief Robert Contee confirmed Friday that the Muellers were married and Madison.com reported they were in Washington to celebrate their 56th wedding anniversary.

The identity of the third victim is being withheld pending family notification.

James Mueller, 76, and Donna Mueller, 75, both from Janesville, Wis., died after being injured in a lightning strike in Lafayette Park in front of the White House.
© Courtesy Michelle McNettJames Mueller, 76, and Donna Mueller, 75, both from Janesville, Wis., died after being injured in a lightning 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 found in "the vicinity of a tree."

It said the two men and two women were transported to area hospitals with "life-threatening injuries."

In this photo posted to the DC Fire and EMS Twitter account, first responders work at the scene of a lightning strike in Washington, D.C., on Aug. 4, 2022.
© DC Fire and EMS/TwitterIn this photo posted to the DC Fire and EMS Twitter account, first responders work at the scene of a lightning strike in Washington, D.C., on Aug. 4, 2022.

Officials said it's still unclear what the adults were doing prior to the lightning strike and why they were in the park.

A lightning strike hits a tree in Lafayette Park across from the White House, killing two people and injuring two others, during a thunderstorm as seen in this framegrab from a video camera mounted on a nearby rooftop in Washington, Aug. 4, 2022.
© Reuters Tv/ReutersA lightning strike hits a tree in Lafayette Park across from the White House, killing two people and injuring two others, during a thunderstorm as seen in this framegrab from a video camera mounted on a nearby rooftop in Washington, Aug. 4, 2022.

White House press secretary Karine Jean-Pierre expressed sadness Friday morning following word the two Wisconsin residents had died.

"We are saddened by the tragic loss of life after the lightning strike in Lafayette Park. Our hearts are with the families who lost loved ones, and we are praying for those still fighting for their lives," she said in a brief statement.

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.

In this photo posted to the DC Fire and EMS Twitter account, first responders work at the scene of a lightning strike in Washington, D.C., on Aug. 4, 2022.
© DC Fire and EMS/TwitterIn this photo posted to the DC Fire and EMS Twitter account, first responders work at the scene of a lightning strike in Washington, D.C., on Aug. 4, 2022.

The National Weather Service had issued a severe thunderstorm warning for the area Thursday evening.

ABC News' Beatrice Peterson, Molly Nagle and Caleigh Bartash contributed to this report.