METHUEN (CBS) – Police are investigating three different incidents involving greeting cards with an unidentified white powder inside mailed to businesses in the Greater Lawrence area.

Each of the three recipients, the Home Depot in Methuen, business in Lawrence, a law office in Haverhill and Image Communications in North Andover received a greeting card through the mail Monday morning with a return address in Haverhill.

The card contained a white powdery substance.

The Department of Fire Services HAZMAT team responded to each of the incidents. Preliminary testing of the powder indicated the substance is non-hazardous.

Local police departments are also investigating where the cards came from.

Six workers at the Home Depot were exposed to the powder and were quarantined as a precaution.

No injuries were reported.