ed.

One of the sources said preliminary field testing continued through the night on the unknown substance and that so far, all the powder tested has been determined to not be hazardous.

Further testing will take place at law enforcement laboratories, the source added.

Senate and House staffers received notices on Thursday with warnings about the suspicious packages as officials began to investigate the letters. On Wednesday, NBC News reported that state election offices in Ohio, Louisiana and Oklahoma received suspicious packages.

As of Friday afternoon, state election offices in Alabama, Arizona, Connecticut, Delaware, Georgia, Idaho, Illinois, Kansas, Maryland, Massachusetts, Nebraska, New Hampshire, Pennsylvania, South Carolina, South Dakota, Tennessee, Washington and Wisconsin have also received packages.

The mailings come less than three weeks before Election Day and after threats against election workers have increased in recent years. Incidents of suspicious substances being mailed to election workers were reported both in 2023 and just weeks before the 2024 presidential election.

Andrew Arenge, Frank Thorp V, Kyle Stewart and Brennan Leach contributed.