The Washington Nationals are investigating an incident during Sunday's game at Nationals Park when individuals unfurled a sign that directed fans to a white nationalist website and called for the deportation of "100+ million."

The individuals resisted removing the banner before fleeing the ballpark.

The team has identified and banned at least one individual from Nationals Park and are working with the Metropolitan Police Department on a follow-up investigation, according to a team spokesman. They did not make public the identity of the banned individual.

"The Washington Nationals vehemently condemn discriminatory and hateful rhetoric, and we strive to make our home field a safe space for our fans," the team said in a statement to multiple media outlets.

The Nationals, who lost the game 7-3 to the Baltimore Orioles, have a daily "Salute to Service" honoring veterans and military personnel before the fourth inning. It was at that time when the banner was unfurled in the upper deck down the first-base line.

An usher attempted to confiscate the banner but the three individuals holding the sign pulled it back and fled, according to a team spokesperson.

Jake Lang, a Jan. 6 rioter and conservative influencer, took credit for the banner on social media.

The Athletic reported that it is not clear at this time how the banner got through security, with the stadium's magnetometers able to detect weapons but would not flag something like a nylon sign.

The Nationals' policy includes guidelines that "signs, banners and fan activities do not distract from the enjoyment of sports games or other forms of entertainment ..." and includes restrictions on size and material.

The policy on subject matter is that as a baseball park, the stadium complex "is not a forum or place for use by the public at large for assembly and speech, for use by certain speakers or for the discussion of certain subjects."

Messages must relate to Major League Baseball, Nationals players and/or management and staff, the entity broadcasting the game or specific family-friendly messages about occasions such as birthdays, wedding anniversaries and engagements.

"Additionally, banners and signs may not bear a message that (i) is slanderous, (ii) is obscene, vulgar or indecent and inappropriate for viewing by children, (iii) contains "fighting words" likely to provoke a breach of the peace, (iv) is presented for a commercial purpose, or (v) contains derogatory matter relating to race, ethnicity, color, sex, sexual orientation, gender identity or expression, religion, national origin, ancestry, disability, marital status, age, personal appearance, familial status, familial responsibilities, matriculation, political affiliation, source of income, status as a victim of an intrafamily offense, place of residence or business or any other category protected by D.C. law."

The Nationals, in their posted guidelines, reserve the right to remove a non-conforming banner/sign or require a guest to immediately stop displaying it.