(Updated at 9:31 a.m. Tuesday) D.C. police have reopened a stretch of M Street NW a suspicious package was reported at the U.S. Post Office at 1800 M St. NW.

The post office reopened for normal business this morning. An employee at the post office said this morning that workers “felt lightheaded” but were not sickened or injured last night.

Authorities said the situation was all clear around 5:50 p.m. yesterday evening and reopened M Street NW between 18th and 19th streets NW shortly thereafter.

Two officers on the scene reported earlier that several people may have been sickened by exposure to the package, but D.C. Fire officials said last night that no toxic material was found at the scene, and added that nobody was transported to the hospital.

Suspicious Package investigation @ 1800 blk of M Street has concluded – no toxic material found.

— DC Police Department (@DCPoliceDept) September 21, 2015

Hazmat personnel were seen setting up a large tarp earlier yesterday afternoon, but rolled it up and placed it back in the truck around 5:50 p.m.