Washington, 24, "reached for and displayed a gun while sitting inside his vehicle" without first informing police who were clearing out the park in the Cincinnati suburb of Sharonville, according to the arrest report. Washington was later released by police.
"We are aware of the incident regarding Adolphus Washington and have been in contact with him," the Bills said in a statement Monday evening. "Since it is a pending legal matter, we will have no further comment."
Washington's agent, Drew Rosenhaus, declined comment.
The Bills selected Washington, a Cincinnati native, in the third round of the 2016 draft. The Ohio State product started 11 games last season, making 21 tackles and 2.5 sacks.
Washington was suspended by Ohio State for its Fiesta Bowl win in January of 2016 after he was cited in December 2015 for solicitation of prostitution in Columbus, Ohio. Washington later pleaded guilty to the misdemeanor charge and entered a program to have the charge dropped.