WASHINGTON — A street in Northwest D.C. has been closed on Monday night as hazmat crews are investigating an unknown substance that was found in an old safe.

It began Monday night at 7 p.m. NBC Washington reports that someone in a house on Kanawha Street Northwest, near Connecticut Avenue and Military Road, opened a 40-year-old safe to find containers with a white, syrupy substance inside.

The street was closed as D.C. and federal officials responded.

See a report from NBC Washington: