Two explosive devices made from drain cleanser were found two weeks ago in Little Seneca Greenway Stream Valley Park in Maryland, police said Tuesday morning.
The devices were found along the Clarksburg Heights Trail in the park shortly before 10:20 a.m. on May 16.
The mixture in the devices -- made from water, drain cleanser and aluminum foil in plastic bottles -- creates hydrogen gas to generate a caustic explosion, Maryland-National Capital Park Police said in a release Tuesday.
Park police from the Montgomery County division responded to the scene and confirmed the devices were undetonated explosives.
Authorities searched the area for any other devices or evidence but did not find anything, they said.
The Montgomery County Fire Marshal's Office is continuing the investigation with park police. Authorities are warning anyone who might find any suspicious devices to not approach or touch them and to notify park police immediately at 301-949-3010.