All four people were taken to the hospital with potentially life-threatening injuries.
The precise cause of their injuries remains under investigation, authorities said.
The lightning was unleashed by a severe thunderstorm that swept across the District just before 7 pm The National Weather Service issued a severe thunderstorm warning for much of the Beltway area between 6:30 and 7:15 pm, cautioning of the threat of damaging wind gusts up to 60 mph and quarter-size hail.
Chris Vagasky, an analyst for Vaisala, which operates a national lightning network, said in a message that there was a “6 stroke flash near the White House that hit the same point on the ground” at 6:49 pm He explained that means six individual surges of electricity hit the same point on the ground within half a second.
Numerous storms, containing frequent lightning, flared up in the region Thursday evening after temperature soared into the mid-to-upper 90s earlier in the day, prompting a heat advisory. Heat indexes, a measure of how hot it feels factoring in humidity, reached 100 to 110 degrees.
The heat-fueled storms unleashed a wind like up to 58 mph at Reagan National Airport and toppled trees around Winchester, Columbia and Baltimore. The torrents also spurred multiple reports of flooded roads around Baltimore.
Lightning kills 23 people in the United States in an average year and has resulted in nine fatalities so far in 2022.
This is a developing story and will be updated.