Envelopes containing a suspicious white powder turned up at sites in Methuen, Lawrence and Haverhill this morning.
Investigators were at all three: the Home Depot store at the Loop in Methuen, the Home Care VNA office at 350 Merrimack St. in Lawrence and the Edwards Law Office at 38 Bailey Boulevard in Haverhill.
At Home Depot, six workers in the store were exposed to the powder that spilled from an envelope that came in the morning mail delivery.
Methuen Fire Department Dep. Dennis Fragala said the envelope was placed in the mail bin. The mail was then sent by workers from the front of the store to the bookkeeping department in the back of the store through a pneumatic tube.
The six exposed workers were were quarantined in the rear of the store in the "siding" aisle.
The regional hazardous materials team based in Danvers arrived at the store at 10 a.m. to test the powder.
In Lawrence, Police Chief John Romero said a similar envelope apparently arrived in Saturday's but was not opened until today.
In Haverhill, lawyer Joseph Edwards said the powder spilled out when he opened a plain white envelope containing a thank you card.
The insurance office of House Ways Means Chairman Brian Dempsey is next to Edwards' office.
More coming on this story as it develops.