WASHINGTON, D.C. (7News) — Six people were taken to the hospital due to heat-related illnesses before and after a concert that was taking place at Nationals Park in the Navy Yard-Ballpark area of D.C. on Monday night.

The Metropolitan Police Department’s Mass Casualty Task Force was called to the area at 11 p.m. after several people became sick as a result of the heat. At that time, five people were taken to local hospitals for treatment.

In a later update, police added that they had also responded to someone sick from the heat earlier in the evening before the concert started. That person was also transported and treated at the hospital.

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Police did not clarify what concert was happening, but according to MLB’s website, the South Korean boy band ‘Stray Kids’ performed at Nationals Park on Monday. Gates opened at 5:30 p.m. and the show started at 7:30 p.m.