The Loudoun County Sheriff's Office confirmed to ESPN that the woman was brought to the Inova Emergency Room in Ashburn by two men, who then left the premises, at around 1:30 a.m. ET Thursday. Nicholson was identified by TMZ Sports as one of the men. The sheriff's office would not say whether Nicholson was involved.
According to the sheriff's office, the case is being actively investigated by its criminal investigations division.
The Redskins said in a statement Thursday that they are aware of the situation.
"We've been made aware of the tragic event and extend our deepest sympathies to the family who lost a loved one," the statement read. "Our team has alerted the league office and is cooperating with local authorities. We fully support law enforcement and respect their process as they investigate the matter."
Nicholson, who has missed Washington's past two games with an ankle injury, was not at practice Thursday after attending practice Wednesday.
Nicholson was arrested on misdemeanor assault charges in December 2018 after a fight outside a bar in Ashburn. The incident was caught on video, but charges were dropped in May because of a lack of evidence. Nicholson also faced a misdemeanor charge for public swearing/intoxication, but the court did not pursue the charge.