Police are responding to reports of a sea mine that may have washed up in Newtown Creek under the Metropolitan Avenue Bridge in East Williamsburg. UPDATE: Not a sea mine, actually. Scroll down for more.

According to police, the possible explosive device was spotted in the waters around 1 p.m. on Friday near Varick and Vandervoort Avenues in Brooklyn. "We don’t know what it is exactly but we’re at the location right now," a spokesperson for the NYPD told Gothamist. There's currently a heavy police presence near the bridge, and the Office of Emergency Management is urging New Yorkers to avoid the area.

Sea mines, also known as naval mines, are self-contained explosive devices intended to damage or destroy surface ships or submarines. Willis Elkins, the program manager at the Newtown Creek Alliance, said he was unaware of any recent instances of the mines appearing in New York waterways.

But he also pointed out that there was a "giant ammunitions factory" located near Newtown Creek in Maspeth during World War II. Additionally, Elkins noted that there is a fuel terminal run by the NYC Department of Environmental Protection in the vicinity of the Metropolitan Avenue Bridge.

"Having an explosive device there would be a little concerning," he said.

The DEP did not immediately respond to Gothamist's request for comment.

This is an ongoing story and we'll update as more information becomes available.

UPDATE 2:57 p.m.: The suspicious device spotted in the river is not a sea mine, but merely a "homemade anchor that washed ashore," according to the NYPD's Bomb Squad unit. There is no threat to the public at this time.