D.C. Code § 5-206

On and within roads, parks, parkways, and other federal reservations in the environs of the District of Columbia, the several members of the United States Park Police force shall have the power and authority to make arrests without warrant for any felony or misdemeanor committed in the presence or view of such members in violation of any federal law or regulation issued pursuant to law, or for any felony that in fact has been or is being committed in violation of any such law or regulation where they have reasonable grounds to believe that the person to be arrested has committed or is committing such felony, and shall have power to take any person arrested by them, without unnecessary delay, before the federal court having jurisdiction over the offense or before a United States Magistrate specifically designated to try and sentence persons charged with petty offenses as provided in the Act of October 9, 1940 (54 Stat. 1058), or before any other officer having authority to hold or commit for the offense. Such police officers shall also have power upon such roads and within such parks, parkways, and other reservations to execute any warrant or other process issued by a court or officer of competent jurisdiction for the enforcement of the provisions of any federal law or regulation issued pursuant to law; provided, that the power and authority herein granted shall not extend to military personnel for offenses committed on military reservations; provided further, that the power and authority herein granted shall not limit or restrict the investigative jurisdiction of the Federal Bureau of Investigation.