"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," Jean-Pierre said in a statement.
At about 6:52 p.m. (22:52 GMT) on Thursday, four people were struck by a lightning while walking in Lafayette Park in front of the White House and were taken to a hospital with life threatening injuries, according to the Washington D.C. Fire and EMS Department.
The two victims of the strike were an elderly couple of tourists from the state of Wisconsin, James Mueller, 76, and Donna Mueller, 75, according to media reports.
The condition of the other two people remains unknown.
Earlier in the day, the body of a man was reportedly pulled from the Potomac River in Northwest Washington, D.C.