Washington, D.C. (Map, News) - The National Park Service was fending off uncomfortable questions Wednesday after it waited 14 hours to tell the public that one of Northwest’s most popular parks was potentially tainted with poison.

The Park Service and U.S. Park Police swooped into Fort Reno Park early Wednesday, moving out pedestrians and throwing up storm fences. Officials said satellite pictures from the U.S. Geological Survey revealed pockets of arsenic on the ground that were nearly twice federal safety standards.

The park has been closed to visitors until the arsenic can be removed, officials said. There was no timetable for reopening.

It took until 9 a.m. for federal officials to call the D.C. Department of Health. The D.C. fire department wasn’t notified until around 1 p.m., a spokesman told The Examiner.

“What this has revealed to me is underlying vulnerability — and I’m shocked to see it so long after 9/11,” District Councilwoman Mary Cheh, D-Ward 3, told The Examiner. “We don’t have a systematic public safety response to public health questions.”

Service spokesman Bill Line defended his agency. He said Park Service officials tried to call city officials Tuesday night but “couldn’t get through.”

“The National Park Service moved with all deliberate speed,” Line said. “Nobody sat on anything.”

As D.C.’s highest elevation point, Fort Reno draws hundreds of visitors daily for its commanding views of the city and Potomac River plain. Two schools, Alice Deal Junior High and Wilson Senior High, abut the grounds of the park.

Line said both school principals were notified of the arsenic problem, but Cheh said Wilson’s principal hadn’t been briefed. In fact, the school was going to hold a fire drill and students would have gathered at the park.

“That is really very, very disturbing,” Cheh said. “There’s got to be somebody who handles these things.”

Arsenic is a poisonous metalloid that prevents cells from breathing. It is common in pesticides and is a common byproduct of World War I-era weaponry. Line said the Geological Survey’s tests were conducted as part of ongoing sampling of the Spring Valley area of Northwest, which used to be a munitions center.

In large enough doses, arsenic can cause massive organ failure. Cheh said the District “was lucky” that the hazard was arsenic, which is fairly stable.

Additional reporting by Staff Writer Scott McCabe.